We have 2 cats, 2 dogs. House never smelled 'off' until we got the cats. It's the kitchen I can smell...it's not bad per se. Nothing really offensive. It just has a slightly 'off' smell. The cats are in the kitchen during the day, but at night sleep in one other room-which incidentally I don't notice the smell in!! No wee AFAIK. They are both neutered. I took the rug out & I do think the smell decreased a bit. There is s soft sofa (ie-not leather) that all the pets lie on. It does get hoovered & covers washed regularly. I spray Febreeze/burn candles & have resorted to Febreeze Plug-ins-which I HATE. Hate fake nice smells, but it's marginally better than the off one. No-one else can smell it. HELP!!!!