I don't use a sniper service myself, and when I bid I bid my max, sometimes I win, sometimes I don't. I'll admit snipers keep the overall prices low as they don't give the other bidders as much time ro reconsider the value, but that's a good thing.

A sniper will put up the same mazimum bid as they would when not sniping in my opinion.

All in all I tend to bid on items that are misspelled or mislisted.