I have a 1987 jem 777 pink, so amazing I bought it new. I played it many gigs and such and is heavily reliced.
Would it lose value if it was refinished ? It plays perfect but pretty beat up and faded, even the headstock lettering is worn off.
Disclosed, you wouldn't get the cost of the restore back, because you can't just restore paint. Anything you put on an old guitar that's new, makes what's next to it look like sh!t. You either do it complete, or not at all. And complete, you won't recoup the cost. But there's too much out there not disclosed, like this reswirled GMC. He probably didn't know better, or the buyer, but it's easy to spot at a glance.