Having been trading (buying and selling) on Ebay for over 6 years it annoys me that sellers of late are virtually blackmailing buyers into leaving positive feedback.
Firstly, they state in their ads that will only leave feedback after you do. I avoid these auctions on principle. I've also heard that they have automated feedback. Leave a negative and you get one in return for some fanciful reason ("not recommended by this seller" or "rude buyer" etc). Ultimately someone has to leave feedback first and then hopefully the other reciprocates in kind. Not these characters! They state that the reason they do this is because they have so many buyers that don't leave feedback. That's the buyer's decision, dont penalise them. What, you didnt get their money?
Any article/item you buy at any shop (a real shop that is), the seller says "thanks very much" (for your money). That's the positive feedback. You go home and test/use the item, then you have your feedback, if it doesn't work. Back to the shop to complain that it doesn't work etc. Are these sellers claiming you didnt pay them, of course not. How is ebay any different? Sellers should always leave feedback when they've been paid. That's the end of the transaction for them. How could they leave anything but positive feedback at that point? It isn't dependant on what the buyer does. But of late it appears to be the case.
I say avoid anyone that states in their auction that they won't leave feedback until you do, like the plague. It just isnt cricket and is a form of blackmail.