I don't bother reusing them, they're so cheap at the LHBS.....and it's easier to dispose of the grain by keeping them in the bags...I'm talking about the standard grain and hop bags, that come with kits or at the LHBS, not the nylon mesh bags that some people use, that are more expensive...Those I would probably re-use, by soaking them in oxyclean and washing in the laundry.