I could see it going XF-AU, and it appears genuine, but it is very obviously cleaned. I've never bought from Denver Coins Co, but I've seen a bunch of their listings and it seems to be, and I'm certain is, too good to be true. I could be paranoid but I think the first suspicion is that they start at $0.99.... while it can be good to increase popularity with more bids, they are also taking a HUGE risk on something like a 16-D, as even in P-1 it is still a good $500 coin. $2475 is not that bad of a price for that coin, but it still has 5 days to go and will likely become an element of unobtanium by the end.
This recent thread might be the one you guys are thinking of. @ddddd sleuthed out the GC sale of a Details 1902-S $1 that was cracked out by this seller and resold. https://www.cointalk.com/threads/question-for-experienced-coin-graders.420878/#post-26649199
I suppose the fact that some people indeed would, however, is likely what this seller is counting on, playing the game with the crackout of problem coins and resale of them raw. I suppose it's kind of a grey area, ethically speaking.