I'm really skeptical about this, because it's not realistic. You've also failed to answer a question.
How often do you clean these tubs?
Just because you don't see it doesn't mean it's not there. Imagine this scenario. Someone sprays urine all over your kitchen floor. It dries up before you get there but you can smell it, and your standing all over it even though it's not wet anymore. Would you really want to eat off of that floor?
Get the newspaper bedding. The puddles are drying up because they're being spread around by their feet and drying up on their feet. Even though you don't see it, doesn't mean it isn't there.
And I'm sure lots of us would like to see pictures of these animals.