How can you tell if you can trust someone?

yeah I do test people. I'll usually ask them the same question multiple times on different occasions to see if they mean what they say or are just telling me things that I want to hear. I also see how they are with other people. their behaviour, their actions.can also help me see if this is a person that I want in my inner circle. in my opinion, trust is something that's earned with time. you can never completely trust anyone except yourself.

but honestly, if I had a really BIG secret, I just keep it to myself. my dad always said that if you don't want anyone knowing about your secret, it's best to take it to your grave as almost always your friend will turn around and sing like a canary if given the opportunity.

I agree that it's mostly a gut feeling, and I probably listen to my instincts more than anything else.
So the length just depends. I may feel like I have to get to know someone first, or I may feel confident that they're trustworthy very quickly.
But I haven't ever trusted anyone completely, I don't think that's wise at all. We are all imperfect and you can't trust anyone to never let you down.
I don't think I test people, at least not consciously. I tend to give people trust as long as they show they care. However much they care about hearing and helping, that's usually how much trust I'll give them, if that makes sense. :]

Trust for me can be an immediate thing. when I meet someone, I can basically feel their aura and feel if they're trust-worthy or not, gut instinct. Even if I do have that immediate trust with them, I've learned to still be 'wary' with it, because people have a way of betraying my trust. surprise surprise.
You can tell you can trust someone with how they handle certain things. By what you tell them, and their actions afterwards, and how it makes you feel. Example: you tell someone that you're thinking of breaking it off with your mate, and a couple of days later someone else asks you why you're planning on breaking up with them. meaning that person you confided it, told someone else. Are you okay with that, do you feel betrayed? etc. and from that moment, you now know that you cannot trust that person with confided secrets. it's all basically asking yourself how much you're willing to put up with, you know? If you're okay with them telling others stuff like that, then you can deal with them. if you like your secrets to remain secrets, then you probably don't want to dabble with a person like that.

To answer your last question, yeah. start people out with small things, and trust them with larger things. ultimately, always follow your gut instinct.

First, trust your gut! it will never lie,
Second, observe
Alot! I look at how their feels are with the subjects I do want to take about, and base it on that.
Yeah, because for one you don't know that person on a personal level, at least get to know them 1 year, so you know who their mood changes during each season.
Heck, yeah, if you don't you will end up eating you won words.

I have learned not to trust and depend nobody because one day they are going to stab you in the back or worse.

It takes like one year and a half it all depends but its real hard to trust someone just like I said on my first answer.

I test people I'm not going to lie but you one day they are going to tell your business like example you tell them they tell there friends there friends tell whoever and all the sudden everyone knows.

I don't think there is any real way to tell if you can trust someone, I think it's more of a gut feeling.

Personally I don't and will never put 100% trust in anyone, I think your a fool if you do, I trust myself and only myself, no one in this world is gonna look out for you or do things in your best interest, most people have ulterior motives, so . don't get me wrong I have plenty of acquaintances and a handful of people I would call my friends, but I know deep down everyone is out for themselves, so I guess I just keep people within arms length and it works for me, I don't feel like I'm missing out on any good times or anything, I just don't put a lot of stock in people in general, I'm from the school of most people are basically bad and they have to work hard on being good.

I don't test. if I have to test then I have my answer, but that's me.

There are some people who I can trust straight away, others that it takes me some time.
I think if you trust people to easily you leave yourself open to getting hurt, which has happened before to me, so you have to be a bit cautious.

I judge it on the vibe I get from the person.

My personal opinion is that people are not lab rats you don't "test them". There are two options, you can see the best in people and give them the chance everyone deserves then be upset if you misread their signals. Or you can put a little trust in someone but never let your guard down. But with that remember you can't have the good with out the bad. Personally I have been hurt many times but I finally let people in and yeah I got hurt but I had fun times that I would have never had if I never gave people the chance to prove me right or prove me wrong.

Trust is hard to build and easy to lose. Not trusting someone can ruin a relationship, but so can putting too much trust into them. I think it's important to start with a happy medium of trust. You can not start off not trusting someone- your relationship will go nowhere.

I have trust issues, because I have never been in a completely faithful relationship. But I try not to bring those issues into new relationships- that is setting myself up for disaster. I don't think it's a good idea to "test" someone for their trust. That will make them lose trust in YOU. Until someone gives you a REASON not to trust them, I think it's only fair to trust them.

You can never really tell. If you don't get burnt on early on, you start to put your faith into that person and you learn to trust him/her. Every person is different in the amount of time it takes to gain trust in the other.

I generally don't worry about it that much. People who are untrustworthy generally make this obvious in fairly short order. Most people are trustworthy and I tend to err on the side of being generous with my trust. People remember being mistrusted for now reason much longer than you would imagine.

I generally give up on people with trust issues fair soon. It's just too much damn work.