This will vary according to how many cats are in the household, how many litter boxes you have and how large the cats are that are using the box or boxes. A good guideline is that if you can smell the box, then you can be sure it's offensive to your cat as well. Add a new box in a different location than the old one and use a different type of litter in the new box. Because your cat has decided that her old litter box is unpleasant, you'll want to make the new one different enough that she doesn't simply apply the old, negative associations to the new box. Make sure that the litter box isn't near an appliance that makes noise or in an area of the house that your cat doesn't frequent.
All animals develop preferences for a particular surface on which they like to eliminate.
These preferences may be established early in life, but they may also change overnight for reasons that we don't always understand. She frequently scratches on this same texture after elimination, even if she eliminates in the litter box. She is or was previously an outdoor cat and prefers to eliminate on grass or soil. What You Can Do If your cat is eliminating on soft surfaces, try using a high-quality, scoopable litter and put a soft rug under the litter box. If your cat is eliminating on slick, smooth surfaces, try putting just a very thin layer of litter at one end of the box, leaving the other end bare, and put the box on a hard floor.