After contacting a seller about a misrepresented set of beads, I had the distressing experience where the seller purchased a small item from me and then left negative feedback to "get even". I contacted eBay but they would not remove the comment. Even more disturbing was the fact that this particular seller lived in an adjacent town (what a weird coincidence, or, bad bead karma coming back to me) and thus had my home address from the shipping label. This made me paranoid for around 6 months and I started using a P.O. Box for eBay sales. After a couple of years of no further problems I went back to using my home address. Still wonder sometimes if I might not run into difficulty from this guy, but it's been over 5 years now.
However in the meantime I have contacted plenty of sellers with mis-rep's but just recently decided to stop due to the sometimes blistering replies...
I've never been blocked, though, as far as I know. But I blocked the aforementioned retaliator.
My all-time favorite mis-rep was the Venetian bead advertised as a "First Century Islamic" bead. Try to get someone to understand that Islam was not in existence until the early 7th century... let alone that the bead was late 1800s Venetian.