My Studio's case smells somewhere between a wet cat, a swamp and an old person's knee-pit.
I've tried baking soda, dryer sheets and Febreeze (not all at once). Be careful with the Febreeze, I sprayed too much in and it ended up smelling like you sprayed the donation room of a Goodwill with it, but didn't really help too much beyond making it smell even weirder.
I think the only thing that helped it was sprinkling baking soda in it, leaving it in until I remembered about it, and then vacuuming it up, and also leaving the case out on the porch in the sun during windy days, but even then it still reeks a little (this was this fall). All with the guitar out on a stand, by the way. I'm going to try baking soda + outside in the sun again when it warms up in the spring.