I like the added insulation that carpet on the floor provides in my Class A. My feet get cold easily. That said, I never vacuum it. I only shampoo it about once every three weeks with hot water and no soap.
Using two exterior floor mats, one with brushes and one with felt helps keep a lot of dirt out of the MH to start with. RV's see a LOT of in/out traffic in a very confined space. Combining that with cooking/washing smoke/vapors is a recipe for rapid filth accumulation no matter what the floor surface. In short, if you use it regularly, RV's get dirty real quick.
I'm looking for a deal on some quality washable, easily removable carpet pads to mount on my kwikee stairs for next season.
Chum lee