I get the same results with a wet/dry vacuum and some basic cleaning agents when and if needed. This is obviously for spot cleaning of accidental spills and such, rather than the entire rug or carpet. When they're dirty, roll them up, take them Dockside and have them professionally cleaned with the big stuff. I can't see the justification for a full carpet cleaning machine considering the limited space a boat has.
If I had reason to keep one on the boat, I'd invest in lids for drinks, or get new drinkers that don't spill or puke.