I don't use any tools myself, but don't have a problem if someone does. As mentioned, it shouldn't really be any different than if they manually put in the same bid at the last second. Being the auction ends at a specified time, last second snipers tend to restrict the amount of emotional bidding that goes on in bidding wars. Sometimes bidders get caught up in it and bid more than they really wanted to, simply due to their emotional reactions. I try to leave my emotions out of it and simply but in my maximum bid, and if someone else wants it more than me, well that's what a free market is all about. No bad feelings there.