Well, I vacuum them at least once a week for the most part, but I need to do some real cleaning. I figured I'd just have to get down there with a rag or sponge and just do it. I'll probably use vinegar or a lemon juice solution, depending on whichever is readily available when I'm ready to start. I wonder if scrubbing with lemons on the boards would work...I have heard that works well on soap scum, so maybe...