We tried Stanley Steamer once
. . . 35 years ago to clean a predominantly white chesterfield. They said they couldn't use their extraction unit, because the color might run. So they ran a damp soapy sponge over it, leaving it worse than before they "cleaned" it. The only options were to throw the chesterfield in the trash, or with nothing to lose, take a chance on one of those new fangled Bissell "steam" cleaners. The Bissell unit brought the chesterfield up like new, and I have been using them ever since.
These cheepie water extraction units run around $200, and do an excellent job. The only drawback it that they are made of cheap brittle plastic along with other cheep parts, that limit their life to about four years.
Bissell has just brought out their new BISSELL Big Green Deep Cleaning Machine
, a heavy duty commercial quality machine to compete with Rug Doctor, and by all accounts, it is even better than Rug Doctor machines by a significant margin. And if I recall correctly, Lowes has started using the Big Green Bisssell machine instead of Rug Doctor for their rental units. At only 2X the price of one of the cheepie units, and a 5 year warranty!
this machine represents the best value in "steam" cleaning units; and the only cleaner to earn a continuous 5 star rating on Amazon:
Amazon.com: BISSELL Big Green Deep Cleaning Machine Professional Grade Carpet Cleaner, 86T3: Vacuums & Floor Care
We do a complete "steam" clean job on the rugs and upholstery in our entire rig at least once annually, and often re-do the carpet after weekends with the grandkids etal, especially muddy wet camping
While the outside of our rig is starting to look like a typical piece of delaminated Winnebago crap, the interior still looks and smells pretty close to the way it was when the rig was new.
Someone mentioned that water extraction units leave the carpet wet for a long time. All units are not created equal. Rug Doctor seems to have acquired a reputation for leaving carpets wet for a loooong time, whereas the Bissell is so good at sucking up the moisture (and dirt implied) that the carpet is pretty much good to go after a couple hours.
We have a Bissell Big Green Clean Machine Carpet Cleaner 86T3
, and couldn't be more pleased with it's performance.