It is amazing how the feed back feature works on ebay, and I am sure many of us either as buyers or sellers noticed how it can be un-fair sometimes. The simple fact that any seller out there will post a (-ve feed back) for a buyer, will be if he/she did not receive their payment. And they probaby waited, exchanged few emails with the buyer, and then probably also filed an Un-PAID item dispute, waited and then finaly filed a strike agaist the buyer if they continue not to get paid. While sometimes the dispute console does work, and may result in the sellers getting paid and closing the transaction with a mutual satisfaction for both parties, some other times it don't. A buyer can always say he had sent the payment, and not prove it. Some other buyers, just don't bother replying, some reply with any answer, so that when they leave you a (-ve feed back), ebay can not remove their ratings to you, because they had used the reply button on the dispute console once. While if they did not reply, you will be able to ask ebay to remove such (feed back), if and only if you file a strike against the buyer.
I would assume that most of the time, any party who places a (-ve feed back) to the other party, will get a reply back with the same feed back. It is amazing sometimes, that a seller might be willing to disregard such action, by just not placing any feed back, hoping that the buyer will do the same. Other times, a buyer might just place a retaliatory feed back. While I find it un-likely that a seller will place (-ve feed back) for a buyer, after getting paid from him. It is likely that a buyer will place one for a seller who filed a strike against him, even if the seller didn't mean to, by choosing "I wish no longer to wait for the buyer", ebay automaticaly places a strike against the buyer, and that might hurt him a little or a lot depending on how frequent he gets un-paid strikes. So in other words, a seller can be willing to absorb the listing fees (which he gets back, if he relisted the item and if and only if he manages to sell it), that he might not get back, and the other features that he might have used in the auction, hoping to re-sell the item, and forget about the night mare had went through, he might still end up getting a bad rating from the buyer.
This was my experience, with the feed back system, I hope this guide gave you some information about how it works, and I suggest you spend sometime reading more about it, it will give you a better understanding of things, and provide you with a better buying/selling experience.