Same tricks in the old audio gear business.
The most annoying was when a bit of old gear turned, of the make that's my speciality,
up that was out of RTE in Ireland, and was just a small add-on unit to other gear.
Slowly, after someone had rewired and modified it ineptly, and it had passed through a few hands,
it had morphed into a 'desirable piece of rare equipment'.
A guy selling it asked if he could bring it to me for appraisal.
I had the factory build file on the unit, so I knew damn well what it was originally, and could tell what had been done to it.
He turned up, I took the lid off, peered inside, and told him about all the horrible wiring that had been added, and what It would need
to be useable and noise-free etc.
He went away, stuck it on Ebay as it was, and in the description, said that I had 'looked at it'.......
hoping of course, that a prospective buyer would see this as a stamp of approval.
Well, I had looked at it, inasmuch as light reflecting off it had gone through my pupils and formed an image on my retinas....!
The guy got one of the rudest emails I have ever sent and he changed the listing.
Incidentally, but smacking of the initial post, the price, over the months, had gone from an initial couple of hundred to SIX GRAND!!!
( Don't get me started on 'provenance'......mind you, I did give friend of mine, a Who fan, John Entwistle's Ronco Record Cleaner....)