Yeap, it hurts. I have about 500 positive and 3 negative. It really doesn't count much. On the contrary, a perfect score it something to be suspicious about, at least in my opinion.
I posted here recently about it. I got two negative feedback in retaliation of two positive I gave, though I didn't want to complete the transaction because the seller was trying to rip me off with postage. when I contacted him, he told me (verbatim) "#$%* U idiot". That pissed me off much more than the negatives.
I had a secondary account, so I instantly bid on his items -unfortunately, an account with few feedback can bid up to a maximum of five articles-. My purpose was to win and leave negative feedback. He found strange than a newbie was bidding more than 400 sterling pounds on his items, found the trick and cancel my bids.
I told him that my new purpose in life was to give him four negative feedback, and as revenge is a cold dish, he could rest assured that I would do. So Terry, open two new accounts, and buy some items with them. There are even auctions in which nothing is sold, just feedback exchange. Once you have the feedback, in the last minute bid one thousand dollars, and with the second account bid one thousand and one dollars. Therefore, the final price will be one thousand and they will have to pay fees accordingly. Vote negative in the very moment. They can have the negative removed and the fees returned, but it will mean a lot of hassle with eBay. Do it until you get tired and they return the money. Tell them -outside eBay- that you are going to spoil all their auctions from now on.
The seller I talked about had recently changed the name. No problem, I'm tracking him so he will never know when will I be there. I had another negative before, and though I also believe it was undeserved, it was a misunderstanding so I didn't see bad intention on the seller. That's the difference.
Raul