Unfortunately very little the seller can do about it. eBay and Paypal usually side with the buyer unless buyer has unusually high complaint or return rate.
Dishonest buyer could buy sealed copy, open dispute claim the wrap was fake or missing and return a different copy that was not sealed or mint. Dishonest buyer could also get the game and return rocks. Dishonest buyer could also buy working Duo or CD system, swap part, and send non working unit back.
There's also case of buyer who buys a lot, then file chargeback with CC company claiming stolen CC. I was hit with that once but since the scammy buyer was in USA I'm sure that hundreds seller who were ripped off over $30,000 from this one buyer all filed counter claim with original ship-to address and the CC company likely went after the person at the address for receiving goods with stolen CC. Never heard anything back and loss of $75 still stinks after about 5 years.
Once in a while seller can win the dispute but usually it's near impossible to win through eBay. The seller may have a better luck filing complaint with post office for postal fraud (ie switched items), with police department, etc.
tl:dr if you can't afford to lose to that 1% scam buyer, don't sell it on eBay. Use something like Craigslist and meet in police station lobby (many are open for CL deals)
