If you think it might be carpets, I've heard sprinkling with bi-carb, letting it sit for a couple of hours (maybe go out with the munchkin) then vacuuming can help - the bi-carb absorbs smells really well. Worth a try if you want a less heavily perfumed option
This works really well. My mums house smelt really musty when we first moved in as kids she did this trick and the smell was gone

The drains are another that can really stink. Mine had to be cleaned out big time as they were GROSS! and smelt horrid.