I think if my litter boxes were changed a little more often, there wouldn't be as much odor. But, litter boxes are my husband's chore, and he doesn't like to do it every other day. (I'm on salad duty, he's litter patrol.) I suppose I could nag at him to do it more frequently, but I don't want to be like that. (I nag about enough other things, already!)
Also, all the friends I have who complain about "odor" only have dogs and/or cats, so they notice the different smell. I think they're homes smell icky, but they don't notice the dog/cat smell, where I do.