A few suggestions:
1. Ask for a money back authenticity guarantee (ONLY AUTHENTICITY, if you overpaid or have buyers remorse-TOUGH! Take your hit and move on. This may seem cruel, but that's why they are called auctions. Please don't use authenticity issues to try and weasel out of your bid. I had someone pull that on me recently with a real U.C.V. item. He didn't honor his bid for over a month, kept telling me "checks in the mail", and then finally said he was told it was a fake and he didn't want it. He dared me to give him a negative, I didn't because he would stain my good record in return, and I already have run into one idiot who did that to me. OK, I am off my soap box now!).
2. Ask for a .jpeg to be sent to you by email before the auction ends. If it is not clear enough, ask for a better one. Again very simple, they won't do it, don't buy it!
3. This sounds easy, but READ the sellers feedback. In an auction I recently bid on I sent the seller the money, 30 days went by of emailing (no responses), waiting etc. for my item to arrive. It never did. I checked his feedback (he had over 1500 positives showing, so I didn't check before bidding) and he had like 12 negatives in a row for scamming people, just like he did me! So, READ FEEDBACK BEFORE BIDDING!
4.Stop giving the fakers positive feedback when they let you out of the deal. I realize you are relieved to not have to pay for the fake, but DON'T build up the feedback and allow them to continue hurting people. PLEASE, NO MORE POSITIVE FEEDBACK FOR THESE IDIOTS!!