On another forum a guy posted like crazy, acting like he was rich and buying and selling all sorts of equipment. He did a bunch of small successful sales/trades to get his marketplace rep up. Then he did a bunch of high price deals all at once and walked away with the merchandise. His account was banned but he came back a month later under a different name. He was easy to spot with a lot of the same mannerisms. When he got to the point of being able to trade on the marketplace I alerted the mods and he was banned again. Even active posters can be out to scam people.
That's the scary part... Just gotta cross my fingers and hope paypal will stand by the victim and not screw them over and put the funds in the criminals hands.