I keep my 1.4 breeders, and the other 20 or so feeders, in the bathroom attached to my bedroom in my apt. The smell doesn't get bad as long as I change bedding (aspen) once a week. I use more bedding than the pet stores do, which helps absorb odors, plus the ratties love to make huge nests in it!
My wife despises the rat smell, and she hasn't slept on the couch yet, so it must not be too bad! I had some mice for a while. They smelled MUCH worse than the rats ever have.