It's the first time I saw "snipers" in this context. "Sniper" is the name we use in Poland for scripts set up to bid at eBay-like auctions. They are the reason I never buy anything from an auction (where I have to bid), and I stick only to buy-now, retail offers. It's because on any auction it's guaranteed that there is always some schmuck that will outbid you by 1¢ at the last microsecond with a sniper script. Proliferation of those scripts makes auctioning a waste of attention and emotional investment.