'Sniping' is a double edged sword, and essentially converts an open auction into a closed bid auction. You can still lose to someone who bids higher than you, and you also run the risk of paying more than you should in order to 'win' an item.
Say you want an item, and it is worth $100 to you, but only $35 to everyone else. You bid the $100, and the bid value goes up to $36. Now someone comes in at the last second and tries to snipe the auction. Either they offer less than $100, in which case they lose because they didn't outbid you, or they bid more than $100, in which case they are willing to pay more than you for the item, and _should_ win it.
Remember that Ebay is a proxy bid system, so you will _always_ lose by just a little bit if you place the second highest bid. In the above example, if you place a $100 max bid and I place a $150 max bid, then I will win the auction with an actual bid of $101 (or $105, or whatever the bid increment is)...you will never know that I typed in $150; the bid history will just show $101.
I use sniping so that I don't get caught up in a bidding war. I decide how much an item is worth to me, ahead of time, and I bid just that amount at the last second, manually. If the bid goes higher, then I just walk away from the item.
I try to scan through completed auctions, to see how much an item goes for, and if it comes up regularly. If something comes up regularly, then I will set my maximum price, and just keep trying until I get the item at the price that I want.
-Jon
-Jon