You run Bonanza? Cool, I have a bill for you.

2 years ago I caught a lady selling handbags (that she didn't really have) from your site. I caught her because she was having people pay through an account with our service (nextproof.com).

Guess who had to eat the chargeback fees? I did

Guess who had to call other people, inform them the handbag they ordered as a Christmas gift was bogus, then listen to them cry? I did

All that to say, if you (or anyone else) has a successful marketplace, shady folks will swarm to you and you will have no choice but to figure out buyer and seller protection policies.