I was gonna say, the inspector first and also the title company, as they have to abide by the inspection. But ultimately the seller is the real A-hole. Wow.
I've had 2 occurrences, one on eBay-sold a Marshall VM and the guy said it 'had a problem' and 'if I refunded him 200 his tech could take care of it'.....then later the same day I noticed he had THE SAME AMP up for sale, using MY PICS for 500 more than what I sold it for. Lol. Won that dispute fairly fast. Next was on Reverb a few yrs back...guy got my amp and tried to return A DIFFERENT ONE of the same model. I had pics to prove it but Reverb sided with the buyer. I shut everything down on Reverb and told them to stuff it. Fuck them.