If really nasty, I throw mine in the wash on GENTLE cycle, warm water, with a LITTLE liquid laundry detergent and a capful of straight Simple Green. Works extremely well with no damage to the pads. I usually throw in any used foam applicators with them. When done, I remove the LC pads immediately, and hang to dry (I use a 1/2" diameter copper pipe, with string run through it, through the holes in the pads. Then the string is tied together and placed over a coat hanger. This allows the pads to dry really quick and maintain their shape.)
Dave