I have a reasonable track record so far. I have only had one to three of the things out of a hundred that I buy from eBay end up being completely not as advertized. For instance, I purchased an old school Xbox from a 'respectable' buyer. The machine seemed to work fine, but the included control was a piece of junk that barely worked after about a week of casual testing. I have found that occasionally a few 'as new' discs would have scratches. By and large I have had a good buying experience from eBay when it comes to games and movies. I used to move a lot of volume through there to resell at yard sales and flea markets, till the thieves became too brazen. Do you do this?
Never. Although I have in the past. I was burned so many times that I stopped buying games, and movies from eBay altogether. I found that Gamestop, and pawn shops are a better alternative, because if the disc do not work you can simply return them for a refund. An even better alternative would be sites like Netflix, Gamefly, and Hulu. You subscribe for $8 a month, and you can watch all of the movies, and play any game you want. I learned the hard way that you should never buy these type products online. I am happy to hear that you have had an overall positive experience buying on eBay, but that has not been the case for me. I love eBay, but I will never buy those type product there again.
I've bought used DVDs from one seller on ebay for a long period of time. Maybe because we've established some kind of rapport, I always get quality used DVDs. I guess to get the best deal from some of these sites, you shouldn't hop from seller to seller. Be a loyal customer and the seller on the other side will do all they can to keep you. In fact, they even offer good discounts which could send a positive message to your wallet.