quite simple. if your going to FE. find good vendors with good feedback, dont fe for first orders, and then FE when you have a good established trust connection with them? top vendors wouldnt want to have someone fuck their feedback, even if they selectively scam, itd still look bad..
the marketplace is here for a reason, to prevent certain scams through escrow, =] gotta love that. but yeah DONT GET SCAMMED! even ebay scams.