If ebay is commited for seller's success, not only the buyer's success, there is a good way to follow. This method will act as a tonic to check the fake buyers.
Once the user registers in ebay, or while bidding for an item, ebay should verify the bank account/credit card details of the buyer as well as seller. Once buyer wants to bid for an item, he should accept to buy this item if he wins the bid and provide the creditcard/online transfer details to paisapay. Then only his bid should be accepted. Once the bid is completed, the money should be automatically transfered to the seller's account. Before the bid ends, if the buyer wants to withdraw the bid, it should be done by the mutual acceptance of both buyer and seller. Note, here buyer is not paying the money in advance. He is only providing the transaction details in advance which will be activated automatically once the bidding is closed. This method is very helpful to check the fake buyers, who can choose whether to buy the item or not even after winning the bid/simply bid for fun.
Ofcourse still there is otherway around like cheques and Drafts. This kind of bidding also should be an option, provided seller can take the risk with fake buyers.
I doubt whether ebay will implement this or not even though it checks this info. Because ebay is always buyer centric website.