You know, I just started selling again and wouldn't you know, one of the first things I sold, I had a conflict. I sold a set of jadite dishes, shipped them immediately after payment and the buyer e-mailed to tell me they'd been ground down, they looked awful, one was chipped, blah, blah, blah. I was shocked! She said she wanted to return them and wanted her posted refunded both ways. She said "after you refund my purchase price AND my return postage, I will leave you positive feedback, if not....?"
I thought she was going to pull a switch on me, but she didn't. I got the dishes back and they're absolutely perfect! So I figure it's buyer's remorse, but I felt so threatened by her comment, that I did refund her payment and the return postage. I don't know if that would be considered feedback extortion, but the whole thing made wish I hadn't started selling again.
I had one negative before and it was from someone who didn't even pay me!!