It's pretty much a good faith thing. I've only bought and sold a couple of things on here, but whenever I've done it, I've dealt with people who've been here awhile, not somebody with just a hand full of posts. That's not fool proof, but it makes me feel better about it at least.
"People say that marijuana smoking is going to get in the way of my career. I say to them that on the contrary, my fighting career is getting in the way of my marijuana smoking." -Nick Diaz