"... this listing for an '88 Model M, which the seller says he's "refurbished", but that it's still missing three keycaps. I can't help wondering why they'd put so much trouble into a board and stop short of such an easy but obvious thing...."
In this case, it appears that "refurbished" means "I cleaned it a bit with Windex and paper towels. Then carefully took and out-of-focus picture."