The best thing to do to prevent that sort of thing is use eBay's buyer filter when you create the listing where you can prevent buyers with excessive negatives from bidding at all.
whats wrong with ebay?
Ebay seems to be having major problems - they "lost" a dispute I opened on a guy (which I had to redo)He had 4 negative(out of 5) feedbacks - he bid high a pair of speakers that he had no intention of buying - He sent me a profanity laced e-mail when I sent him a invoice and he also sent me another one when he left the neg. feedback taunting me about it -ebay let the guy leave negative feedback on my perfect account and said they cant do anything about it - I've sent a couple of emails to ebay(after finding the buried email link) with no response from them except that they cant do anything about the feedback. anyone else have a problem like this?