My first response is.. you can't tell.. that until tested, there is only your best guess.. most likely not the response you want to share I know

A more detailed answer, is it depends on so many factors, I believe that with careful screening you can choose more carefully who gets let in, and how they get certain information, but the bottom line is, each new test will always be a challenge, each new hardship will show the cracks or the strength of those around you.

this is a very touchy subject to talk about on a public forum, and so while I have a lot more that I could say on it, I won't..

By asking a boat load of leading questions along the lines of what one is trying to work towards and listening carefully to the answers then following your gut instincts.

What type of question/answer gets their motivation meter in high gear is also a concern; are they always moving the conversation off the directed path? Go down that path in detail and see if its something you can live with or if its a red flag for your comfort zone. Question, then let them do all the talking. Listen carefully. If you run your own mouth off, you won't hear anything.

Make a totally off topic loaded statement about climate change and see how crazy they get when you get into that debate. This is a good time to run your mouth off. That will soon give you a picture of how their reasoning works and if they can hold a conversation with out calling you a dumba$$ or something nastier and sounding like they mean it. Eventually you just have to make a call.

Pay attention to your dog if it gets to a personal face to face on home ground. I am not kidding on this one. A generally kind hearted loyal dog can root out the baser qualities of a human and will let you know if someone is a potential threat on its turf. A dog just knows if someone can be trusted with their people. If Fido doesn't want anything to do with the candidate, than you shouldn't either even you think they are the greatest thing since sliced bread.

The rest is just having a good lucky feeling. (crap shoot)

how can you tell the difference between people preparing for the future and those that want to kill other people. People they identify as "The Other".

You cant, I cant, no one can. Certainty of intent in the human species is like looking for unicorns or rocking horse shit...good luck finding it. We are tribal, we anger too quickly, act without thought, delude ourselves with wishful magical thinking, are easy fooled.. often by ourselves,self medicate with all measures of substances and almost beg to be lead and protected. The prognosis for our species isn't good.

You can only try and shave the odds a bit in your favor..... I cant really say what to look for but have learned overtime there are indicators that should raise red flags as they are indicators to those prone to psychopathy of one form or another mild or sever. Those quick to anger...bad sign...Those upset by thoughts and ideas that are different than theirs as in they are always 100% certain......again bad sign you should never be 100% certain. Those enthusiasticaly sworn to any political ideologies, its a sliding scale 0 to 10, and those you are around that are past 4 you should take the safety off)
Same for members of any of the magic sky god clans, generally for me when they start going past 3 on the scale, I take the safety off if I think they are 4 or greater then with my other hand cover my wallet and back away while watching their hands.
Addictions...again a bad sign, those who have fought them and won...maybe a good sign.....
That's pretty much all I got....its less than it appears because there are always individual exceptions that will surprise you, and you will unfortunately generate false positives, but no method is perfect.
Maybe just take a coin and flip it, flip it as many times as needed to get it to land how you like.....yea coin flipping, go with that, im certain of it.

Odduck, my dog would lead a crazy mob right to my front door for a pat on the head, 100+ pounds of friendly stupid, want to trade?

how can you tell the difference between people preparing for the future and those that want to kill other people. People they identify as "The Other".

You cant, I cant, no one can. Certainty of intent in the human species is like looking for unicorns or rocking horse shit...good luck finding it. We are tribal, we anger too quickly, act without thought, delude ourselves with wishful magical thinking, are easy fooled.. often by ourselves, and almost beg to be lead and protected. The prognosis for our species isn't good.
You can only try and shave the odds a bit in your favor..... I cant really say what to look for but have learned overtime there are indicators that should raise red flags as they are indicators to those prone to psychopathy of one form or another mild or sever. Those quick to anger...bad sign...Those upset by thoughts and ideas that are different than theirs as in they are always 100% certain......again bad sign you should never be 100% certain. Those enthusiasticaly sworn to any political ideologies, its a sliding scale 0 to 10, and those you are around that are past 4 you should take the safety off)
Same for members of any of the magic sky god clans, generally for me when they start going past 3 on the scale, I take the safety off if I think they are 4 or greater then with my other hand cover my wallet and back away while watching their hands.
Addictions...again a bad sign, those who have fought them and one...maybe a good sign.....
That's pretty much all I got....its less than it appears because there are always individual exceptions that will surprise you
Maybe just take a coin and flip it, flip it as many times as needed to get it to land how you like.....yea coin flipping, go with that, im certain of it.

Odduck, my dog would lead a crazy mob right to my front door for a pat on the head, 100+ pounds of friendly stupid, want to trade?

My current dogs are like that, young and somewhat stupid and in love with everyone. Just last night they proved otherwise. A pizza delivery ( yes they have them in rural areas) gone wrong. Dude didn't have a clue where he was. Knocked on my door and the dogs came unglued. They have never done that before. I would have sworn a guy with a pizza would have gotten an easy pass. Guess not.

The dog I had when I was a teenager was a big softy as well. He blew out a double paned window (thick panes 4" apart) and a chicken wire fence four feet away on the outside of the window in order to save my hide. Don't underestimate your friendly stupid. He just hasn't been put to the test yet. Unless he does not consider you part of the pack, if someone gets aggressive with you, he will show his true loyalty. It takes a very special kind of person to set a softy off without provocation but it happens. I have a lot of faith in dogs. They don't have to be anti social to do their job.

On second thought, since none of us are getting out of here alive anyway, and time is short, instead of worrying about who will do what some time in the future, worry about living now and start by getting rid of all those who are annoying. I don't want to be annoyed while I am here, simple as that, Identify the annoying, you are certain to get that 100% correct, buy them a bus ticket, or send them out for mix and lock the door and don't let them back in. That will at least make the time you have left more enjoyable, and wont generate false positives.

.....I am not helping, am I? Have to go, looks like I am being sent out for pop.

Side line- dogs, I have to agree, my boy was the life of the party, he appeared to love everyone he meet, I would have said that I looked to my big girl to judge folks, because he was the happy, happy.. until the time I was threatened by a male while alone, he turned into a snarling, fanged ball of fur, and when I stepped out of my truck with him on the end of the lead, begging to be turned loose, the growls and snarls coming from the rest of the pack still in the truck (and the crow bar at my side) as I looked at him, got the point across..

He had followed me and then blocked me in and then we had just sat there for a while waiting.. before I got out to confront him. Never thought I would see my boy do that, and he never did before or again..

Matthew 7
15Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. 16Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? 17Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. 18A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. 19Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. 20Wherefore by their fruits ye shall know them.

Truth is you need to get to know people, see their actions, before you can trust them.... or not. Most people I find are a disappointment, which is sad.

As for dogs. I miss mine. RIP. She'd corner a stranger and wait for me to find out if they were okay or not. It didn't matter if it took hours before I got home, she'd keep a person waiting for me. Once introduced, they were okay with her and she'd beg for pets.

I've thought about this as well. My biggest problem is myself, I've been able for the most part of my life, able to stay out of trouble, very few fights. Three, three fights and only one I had to use my firsts; I was almost 6 feet tall and 180Lbs at 14 years old, and an older brother and sister who were and are tougher then nails. They and their friends were allowed to beat on me but no one else.

The situation of, "neighbour killing neighbour" in the middle of the night is a terrifying thought. My father would be in charge, be spent 37 years in the military and many deployments overseas. He's also a stores men by trade and the toughest son of a bitch that I'll ever know and love.

As for the OP, all I can do is offer my condolences to your friend from Eastern Europe, and to you C5 on the loss of her husband and your friend. Sorry.
We've had it to easy for to long and have been "fortunate" to be able to have the luxury to waste food, fuel, time, family... If, when there is a food crisis here because who knows how much longer our logistical systems will hold out, it will turn to neighbour against neighbour. My children need to eat and so do there's. It would become as I enjoy saying, "A sticky pickle indeed". The only thing you can do is be yourself and she may trust you in time. Time and trust.

without sounding alarmist or being mean to other like minded souls, you cannot trust ANYONE fully, i have seen friends of decades turn on eachother for what seemed like pitifully small reason, ....Human nature is to survive...no matter what the cost, friendship, is a luxury the true prepper cannot afford to let cloud his or her judgement...... yes it's great that we on these forums all share a common interest or similar philosophy, and we can swap ideas and info to help each other, but that really is as far as it should go,

.....in fact, reason would dictate that we have already given away too much, for now anyone who looks at this forum has an idea of how many preppers are in their area, and across the country or indeed world, prepping is an individual and solitary thing, that doesnt really extend outside of family and real close friends.......

the best and probably the most successful preppers, ...will be the ones NO ONE even realises ARE preppers, they secretly compile their stocks, and take what measures they feel fit for their survival, ....and tell NO ONE.....those are the ones who will stand the best chance...in the real world, (not hollywoods idea of how things are)
people will turn on friends family and even the lovable dog if the situation arises, you simply cannot underestimate an individuals will to survive and what it will make otherwise rational and friendly people do, ....

.ask yourself this...your lovely friends and neighbours...really great people, ...did you share the fact that you have stocks and supplies and weapons set aside for "the day" ...if TSHRHTF....then where do you think their first port of call will be??, and how do you think they will react when you tell them that ..as much as you want to help them, your supplies will not stretch to help save them too.....how long will it be before they not only attack you for your supplies, but also gather others to aid them in overpowering your defences........well i'll tell you....probably a lot less time that it's taken you to read this message.....it's a hard and horrible truth...BUT IF...IF it all goes to Sh*t....you cannot trust a single person other than YOURSELF, your own wife daughter husband or son, may well decide that they want there boyfriend or school friend or nice mrs doo daah from down the road to come in, well thats great, but what about the family and friends of the one they want to let in.......your supplies are FINITE and you may have to make them last a very long time, ..so if you are a serious prepper, not just a pass timer who likes to buy loads of stuff just in case, .you have to get it into your mind right now....there are no friendlies that you can take for granted....you might be better off taking the sad hard line..that when the S really hits the fan...there can be no complete trust and there may well simply be no friendlies...............