Unfortunately, often times you don't know until after the fact, who you can trust and who you can't. I, sadly, used to be very trusting of most of the people I knew and worked with. It took a very difficult period in my life to open my eyes, and teach me not to give my trust to anyone. When folks you thought of as good friends go out of their way to fuck you over for no good reason other than they can, it taught me to make people earn my trust, and my trust has many levels. I may trust someone well enough to go to the range with, but not enough to try to ride out the apocalypse. If someone, out of the blue, tries to be my best friend right off the bat, I absolutely don't trust them cuz I feel like I'm being played. I believe, sadly, it takes getting screwed by folks you did trust to truly teach you how to be a good judge of character. Maybe my past has made me cynical, but there are few people that I can't just walk away from anymore. I hate that it's like that, but I consider it self-preservation.