I do because they always manage to get dirty (and I have marking lines I want to wash out). The white one that I'm working on now.. I don't know how it got so dirty! I'm in a pet-free, food-and-drink-free room and I always wash my hands before I sit down. I've been very careful to make sure that this one hasn't touched the floor (I'm not always so careful!) but it will still have to be washed.