It's a philosophy that I stand by. I've encountered so many people who easily and gleefully throw folks under the bus. What makes a healthy body think that I would want to be put into that situation? When I meet people (professionally or personally) who don't have the most ethical or consistent behavior, I will stand back and put off the possibility of friendship for a later time or date. So often the untrustworthy want to be fast friends with me. The harder someone tries to be my best bud, the less I want that individual in my spheres of influence. I see this at work all the time; usually the brown-noser or wannabe Queen Bee who wants to be in charge of things. Of course, there are also people in my life who suffer with bipolar illness. Some things can't be helped. Being a close friend with someone who can snap at a moment's notice can be a challenge. I haven't quite mastered that yet.
I have 3 catagories for people in this world. Allies Neutral Enemy 95+% of the people I know personally in my life fall under neutral, a small % allies and small % enemy. Neutrals can be anyone from family to friends and acquaintances. They won't get much out of me yet pose no threat. My allies I will do anything for and vice versa and my enemies I don't give two hoots about.
I just go with my gut feelings. I'm pretty intuitive that way. I like to think that I'm a friendly enough guy, though, I might not look like one at times. I give people chances, and my general approach is that, as long as you don't deliberately try to fuck me, or my family or friends over, then I'm chill. I tend to have less tolerance to those who try to screw my family/friends over than the ones who try to directly upset me, it seems. Usually time might also help me in terms of determining whether someone is "trustworthy" or not, but sometimes I know after a relatively short period of time that they are legit. Conversely, I've been fucked over by people I'd known for many years in the past where they essentially also caused my family some serious inconvenience, so time to me isn't always a guaranteed ingredient when it comes to knowing who I can trust and whatnot.
I usually give someone the benefit of the doubt. They have to really repeatedly piss me off to make me angry and distrustful. And some of these people do seem to have issues they know about, but don't actually work on in a constructive way. However, this seems to be the human condition for the most part. You have to figure out who you can tolerate and who, with all ther foibles, brings more to your life than they take. Those are the people who you trust and who remain your friends, hopefully for a long time.
My wife tells me I have trust issues. I do. It takes a lot for me to let someone into my circle. We all have our hangups.
Some may try too hard because they're seeking acceptance. I think that's what most people "want". They may have experienced rejection from their home of origin... And you know if you're rejected as a child you either don't try, or try a lot...usually expecting rejection either way... A little positive acceptance might help people along the way. Unless they're asking for money, what's the harm and trying out a possible friendship for awhile. "No" remains in your lexicon.