Mine are pretty clean too. I usually don't wash them prior to refrigerating them unless there's pooh stuck on them that won't come off with a paper towel. There's a coating on them that acts as a natural antibiotic/barrier and washing them washes it off. The eggshell is porous so once the coating is off, bacteria can get in the egg. This is what I've heard anyway. If I have a dirty egg, I'll wash it in hot water right before I use it. I keep my nest boxes clean, and that seems to help...unless it's muddy, and then you can forget it. I have a friend who uses a little bit of sandpaper to rub off the stubborn stuff, but I'm not sure if that rubs off the coating or not. Seems like it would, but I really don't know.