The little compagnucci's aren't bad, they barely smell. My 5b on the other hand did... it smelled like an old, worn out, two stroke motorcycle. I was living in an apartment at the time and couldn't leave it outside, so I picked up a large rubbermade tub and put a few boxes of baking soda in there with it. No stink after that. It would also slide under my bed, and out of sight.