When I had my rats in their old cage using fresh n comfy, I had no smell really. I recently got a critter nation and they smell is pretty bad. They've been doing pretty good for using their litter boxes, but the other day I cleaned everything, scrubbed the plastic, new litter, etc and they still smell. They had peed in a bed I had for them so I threw that out. Those who have critter nations/no bedding, how do you deal with the smell?