Do you say anything to an opponent who is obviously giving you bad racks? If they're positioning balls to where I might be at a disadvantage after the break, normally I don't say anything, I just play them how they roll. I don't think I've ever asked for a re-rack. If they're racking the balls loose, which may be hard to spot until after you've already hit the break, normally I'll ask them to tighten the rack.