The world is full of honest people but there are enough arseholes out there. The internet facilitates them (and maybe amplifies them).
Ebay and their ilk are basically giant anonymous garage sales. My starting principle with these platforms is: "don't spend what you cant afford to lose". You are trusting the honesty of sellers in the listing details and the photos. It can range from generous and transparent, to ignorance, to downright lies. If you feel conned, you then have to fight through the bureaucracy of faceless corporations for recourse. You can adjust your sense of risk based on the information provided and the history of the seller... but the risk is never gone. Purchases are always sight unseen.
.... For purchases >$2K... you'd better be happy gambling that amount or damned sure about what you are doing.