I think we all know what it is like to bust open your favorite pack of cards that you have been using for weeks to find that they don't fan, and they clump, and they don't hold together. That feeling sucks. I recommend using fanning powder, which is cheap, to decks that don't handle well anymore. I would not use it on new cards because there is a chance that it would screw up your sleights, but on an old deck, it will bring you fans and sleights up to par.
