Joe, the reality is that many eBay bidders simply do not bid their highest. In an attempt to get a deal, they lowball their bids, and then incrementally bid higher, a little at a time, when they see others outbidding them. BUT if there are no competing bids, then often they leave their bids low. That is where we come in.
For example, if Joe Blow bids $20 on an item and Joe Sixpack outbids him at $22, then often Joe Blow will increase his bid to $25. Then Joe Sixpack bidder increases to $27 and Joe Blow, in response, increases to $30. It becomes a cat and mouse game,until someone blinks. Sometimes people get annoyed that someone else is bidding against them for "their" item and the bids get way out of control, far more than they ever had planned to spend.
On the other hand, if Joe Blow bids $20 and no one else bids, he may well leave his bid as is. Then I come along and bid $35 at the last second, winning the item. Or, even if Joe Blow and Joe Sixpack were engaged in a bidding war and are nickel-and-diming each other up past the $35 mark, I may jolt both of them into sobriety when my $48 bid takes the prize, leaving them in the drunken dust.
Sniping usually works because of the element of surprise, and because it is in the nature of so many proxy bidders NOT to bid the most they are willing to pay, at least at the outset. Some of our snipe amounts would indeed be outbid if they were bid early in the auctions, but more often than not, we snipers lie in the grass, watching Rick's Regal Proxy Bidders fight over a prize that they will not win.