I used to make a bit of money on
ebay flipping cameras from 2 am auctions and/or cameras with bad spelling into the title and on to buy it now. Having spent quite some time looking at bikes I can see what's going on.
It's basically split into five. Online retailers. LBS selling second hand buy it nows with collection only, basically using ebay as a advert and that's fine, it's very rare that any of these places offer delivery and that's not fine. Thirdly you have the people who bought a bike a few years ago and don't understand depreciation (selling to people who do not understand depreciation). Then you have people who restore and flip, at first I thought these people were getting over ambitions with pricing but people will pay for "vintage" brands in interesting colours so fair enough. Lastly it's bike thieves pretending to be one of the others.
I'm 100% certain my ebay bike came from a retired chap who restores and flips, from his shed, I know this because I did some cunning detective work by going though his feedback history, also one of the pictures had a middle aged woman next to a open man cave type shed holding said bike upright and two cups of tea. She looked quite unhappy about it.