Some people tying to sell used junk might 'lose' part of shaft so demonstrating how it works is impossible.
Years ago, a AC Round Baler was advertised as 'in working condition'. When I talked to the seller, we agreed to 'bale' a roll that I would pay for to demonstrate it actually works. I drove several hours pulling a trailer only to see a rusted piece of junk that had not run in a LONG time. He did not have a tractor either! Seller tried everything to get me to buy since I was there and had a trailer.

Some people are really low down.