I have a lot of people in the mobile homes that use that unit after a few times and no luck as the carpets get older they call jack on the carpet. Sometime I get good results so times NOT. The age and type of carpets play a roll and if there are pets and they grind it into the carpets you know what happens. They think they are saving money but over a long time period the carpets just don't clean up well. jz.
Knowing that the Kirby uses a high quality polymer shampoo now, there are a lot worse ways for a homeowner to improve the appearance of their carpet...