Yeah, chuck ‘em in the wash with regular detergent and a little bleach or vinegar (but not both). When you dry towels, remember not to use fabric softener, as it makes the towels less absorbent. As far as preventing mildewy washcloths, the only thing that will do that is to get it out of the damp environment. Try keeping it on your regular towel bar to dry and just grabbing it before you step in the shower. Either that, or buy a few extras and switch them out every day or two.