Yes, I sold some of my unused, but expensive aquarium equipment on a well known auction site, and one person claimed they did not receive something. It was sent to another country, at the time with incomplete tracking. I refunded the money, but I think this person just knew how to scam
I feel bad for these sellers. It is a lot of work to sell on an auction site, and to have to turn around and do it all again must be so frustrating