If the litter box is dirty, your cat may abandon it to eliminate on inappropriate surfaces like the carpet outside the litter box, the sink, or even the bathtub. We recommend keeping the litter box spotless by scooping immediately or as soon as possible after each use. We also recommend washing the litter box once a week or bi-weekly with mild soap and warm water. Avoid scented or citrus cleaners because cats have highly sensitive noses and will object to the strong odor by possibly refusing to re-use the litter box.