I have posted this before, in a modified form, in other threads. It may help you understand how eBay's proxy bidding system works.
The other bidder does NOT know how much your bid is. If you place a high bid--even one with five seconds remaining--your true max is not automatically revealed. All that is revealed is the amount necessary to make you the high bidder. For example, if the item is currently going for $26.50, and your snipe is for $35, your last-minute bid would simply raise the price to $27.50, not $35, assuming no one else bids higher. If someone else puts in another (even a last-minute) bid for $30, then you would still win, but for $31. But if that other bidder placed a bid for $50 anytime during the auction, then there is no way you can win, since his snipe would raise the winning bid to $36, one increment above your snipe. That bidder had no way of knowing that you bid $35; he simply placed a bid for a higher amount, and would have done so, regardless of whether or not you bid. The only difference would be in the precise amount paid by the winning sniper. Ebay always lists the bids in order of highest to lowest, NOT in chronological order.
This all points back to the same thing. Decide your max well in advance, then bid that at the very last second, through AS. If you win, great--and you
will win most of the time, unless you are bidding pittances. But when you do lose, it is usually because someone else was willing to pay more than you were.