My cat was spraying the hallway wall outside our second bathroom for an unknown reason. I scrubbed the wall until the paint came off but could not get rid of the discoloration and the horrible smell. It soaked into the drywall or something. I even tried painting over it. After using this just twice, once sponging it on and once putting it in a spray bottle and soaking the wall and letting it dry on, the smell is completely gone. I repainted and you can't even tell. My cat has also stopped using that spot.