If you're really, really into sniping you want to know everything you can learn about your competition. If you track someone who's bid against you, you can learn a lot about his spending limits and bidding habits (Is he also a sniper? What's his time frame for bids? Does he knee-jerk and counterbid every time someone tops his bid or does he wait 'til the end?). This kind of information enables you to plan the timing, and more importantly the amount, of your snipe bid. Next question?