Case in point:
A few weeks ago, I met this guy at a metro station not too far from my house, we hung out, went for a couple drinks, smoked a joint together and then I needed to come home to drop something off. I invited the dude into my house and we hung out for a few mins on the couch. He then asked if he could use my computer - which is in my bedroom - so I said sure. We go in, he logs into his email and then asks me for a glass of water. I fetch him some and return. We then leave the house and head out to meet a friend of his... We get to a bar and I'm smoking, so I can't go in and he asks to use my phone. I gave it to him and he goes into the bar, never to be seen again. I spent the rest of the night stalking him, trying to get my phone back to no avail. The next day, I went looking for my digicam, only to see the empty case sitting on my bureau. The fucker thieved it while I was getting him water!
On the other hand, sometimes a person is totally the shit and your faith pays off:
Yesterday, I went to test a '91 Peavey Classic 50 212 amp that I found on CL. The guy brought me into his jam spot, let me try the amp and we discovered that there was a strange buzzing sound coming out of it when I my settings were bass heavy. I figured that maybe the speaker needed re-coning or something, so I offered to take the amp anyway, try it out with another set that I have and if it didn't work out, I'd give him back the amp and he'd return my money. As we were parting, the dude says to me: "You know what? Why don't you just take the amp, keep your money and email when you decide whether you're going to keep it or not?" Obviously, I was like


So now I've got a (60lbs!!) amp here that I haven't paid for... the dood doesn't know me from Adam and there's no guarantee that I won't run away with it. Luckily for him, I'm an honest guy and I already emailed him about it but... WOW!
Anyway, would/have any of you had similar experiences in either of these cases? How do you tell an honest person from a dishonest one, without the benefit of time or independent confirmation?