As khaleel said, they are always good for something, for me when they get tired you can make gimmicks out of them, so there is nothing to waste.
gimmicks means editing the deck to preform a trick, like glueing cards together to make an extra-thick card so that you can find it, or cutting a hole in the deck to hide something.What do you mean by "gimmicks" and "tired"? Sorry for all the questions.
Oh, what i meant was that when they get a bit destroyed or, not a good deck (anymore), i mean like bad fans and something that makes a deck pretty much (destroyed): Scratches, etc..What do you mean by "gimmicks" and "tired"? Sorry for all the questions.