Cat pee anywhere in the house can make your entire home smell like a litter box. Cats' urine contains strong-smelling proteins they use to mark.
Most cats learn to use the litter box without much training. However, sometimes a cat might have issues urinating outside his litter box. This is different than a litter box problem, and if your cat is urine marking it needs to be dealt with in different ways.
Cats are meticulous animals and usually confine their toilet behaviour to the litter tray or garden. The smell of cat urine or faeces in the house.