Usually bothers me as well, however one dealer/seller whom I've dealt with in the past (Wayne Varner Shoebox cards) doesnt post scans of backs to a lot of his cards, however he's the lone exception that you can be promised is rock solid when he says the back is clean and no paper loss,writing. Wayne is probably the only guy I would trust buying a card from with no scan of back. Also just bought a BEAUTIFUL E95 Plank at an AMAZING price off of him last week......did I mention Wayne is an awesome dealer?
