"Item not as described" is the secret passphrase. Seller has absolutely no recourse. I've never tried it as a buyer, but as a seller it's been 100% effective in the scammer getting their money back from me.
But, really, it's okay to lose money on some transactions, especially if you reduce buyer/seller stress on other transactions.
Except, I suppose, how do you validate THAT?
If I'm the seller, and you send me back an empty box or an old iPhone 3GS, what do I do then?