Only the newbs do it.
Vets know that 1)eBay buyers are typically dumb enough to drive the price up on their own and 2)there are a lot of zero feedback scammers and zero feedback "Free iPod" people who bid simply as part of a promotion that do a good job of driving up prices.
You just have to use some caution; if there is a zero feedback high bidder with only a few hours left, I typically contact them to see what their intentions are. No reply = cancelled bid and blocked bidder.