Oh, to get into the mind of a cat. Even after many years, I still don't know why cats do many of the things they do! Many cats seem to like to urinate on throw rugs. This can be because many like the soft feeling of them and the ability to dig in them. However, any time a cat is not using her litter box, I recommend a check-up. Cats will often not use their litter box with medical conditions like a bladder infection, bladder stone, diabetes or lower urinary tract disease.