To see is to believe, how can a blind give trust to someone?

that is why some learned from their experience. I do give my trust easily to people when I was young, like gradeschool. But when I reached highschool that trust broke and its hard to give my trust again. I can be friendly anytime, but It doesn't mean I trust that person in an instant. Actually we can feel who are the person who we can trust. I don't trust gossiper, like all of their lifes they are talking nothing but about other's peoples life and criticize them, like those people should be look funnier in their opinion.

I agree with you, behavior is a main factor to gain trust. But also, having a conversation, let's say an introduction, it can be tiny, just for few moments.. you can see the intentions from that person. You can see how a person react when you are having a conversation, if he looks around means he doesn't really care about what you are saying. That, combining with behavior pretty say much things about that person. Other way is to observe his movements, his facial expressions. There are lots of ways to know if we can trust 100% in a person.. or just 20%. But mainly observation about their behavior and they way to talk says it all.