Hmmm... Seems to me you all are making this more difficult than it needs to be. Now granted, my carpet has never seen shoes or any major spills outside a beer or two here and their...
Twice in four years I pulled out and onto the driveway, spray it down with the garden hose, sprinkle in whatever laundry detergent the wife has on hand and scrub lightly with a short bristle brush on a pole and rinse. Done in a about 20 mins, hang on the deck to dry, looks brand new!
I do pull it out and use the house vacuum a few times a season also.