What is the best litter for a cat box? We currently have at least 2 but up to 4 using the box. With my advanced sense of smell it seems as if the box is always dirty, even right after it is bleached down and new litter put in. Is there something that will help with the smell and clumping? I currently use tidy cat, and the box does have an odor thing on top to try and pick up some of the smell. I hate even being in the house with it at this point. I am tempted to move it down stairs but then afraid nobody will clean it.