I'm in the "not often enough" group, I guess. I have never replaced the litterbox in the 4 years I've had it, and I have only replaced the entire contents of the clumping litter maybe twice? Funny, because I'm an "anal" person about cleaning and germs too, but since the box is downstairs in the laundry room, I don't really notice it. I think I'll replace the litter more often though, because it really does get stinky from the little crumbs that fall off of the clumps. I do wipe down the rim and/or sides if kitty "missed" the box.

I'd like to hear, too, from anyone who has used that rounded litterbox that you "roll" to clean it. It looks really interesting, but I couldn't quite figure it out in the store.