Special water?
While I admit a roomful of rabbits might smell, our 1 rabbit rarely got to the smelly point as she was trained to use kitty litter.
We use special rabbit litter and our rabbits are well trained, but they live in the house with us. We were told by our vet not use kitty litter because it can be hazardous to the rabbits. But even using kitty litter, as we did when we bought our first rabbit, does not eliminate the problem. Rabbits go way more than cats or dogs, but when they have to, they can hold their business for quite a long time.
I have noticed though that our spayed female rabbit smells a lot better than our non-neutered male.
The special water is an herbal mixture that reduces the smell tremendously. If we did not have the water, we would probably not have the rabbits -- my husband does not appreciate the offensive odors.
These are my son's pets. He has two rabbits, a guinea pig and an Egyptian tortoise. The guinea pig smells too, but not as bad as the rabbits; she gets the treated water too. The tortoise does not smell.
Funny, somewhere in the world all these pets are on the menu.