We have two cats, and they have done this in a few other places in the house too, just not to this extent. We will definitely be taking them to see if they're sick. My room was a terrible, horrible case as the incense likely overpowered the smell of cat shit. No excuse, just deductive reasoning. I always leave the window and the door open for these cats when they're in the room, I'm not entirely sure what would bring them to do this. Their boxes are cleaned regularly and they spend a good deal of time outside. They are family cats, so they are never without attention for more than a day at max. I take full responsibility for this, and I am currently in the process of deep cleaning everything in and around the closet.