I think as long as you pay with PayPal you're fairly well protected. That said, a lot of those Facebook guys only want to deal in gift payments which, to me, is a little sketchy. I really don't care who "vouches" for you. If I don't know them, and know them well, I certainly am not gambling with my money by sending them a gift payment. I'd rather pay extra to cover the fees if that's the problem. If they can't accept that, then there's probably a reason because taking gift payment "should" only be about the fees.