I personally avoid those who hide their feedback. If they hide it then they obviously have something to hide. We were selling a car and we had a member who bidded on it. about 30mins before the auction was due to end he sent us a message saying he had bidded on the wrong item, and could we react the bid. At the time I didn't know how to and so I just waited.
When the auction finished there was no more bids and his was the winning bid. I sent via ebay a non payment which if he had clicked on that he had agreed not to purchase the item we would of been reimburesed with our losses (about £30) but because the prat clicked on he had agreed to purchase the item we are now out of pocket of £30. ebay say that there is nothing they can do.
Apparently he did it again with somebody else and no his feedback is private.