In the past 35 years we have used them ALL as well as quarterly pro cleaning...the more you clean your carpets the more dirty they will become! All are coated with some kind of dirt/stain repellent and that eventually gets washed off with the cleanings.
I finally had to resort to using a hot water variety and the hot water I used had dissolved Cascade in it(relax the carpet people told me to try it), then strained out. The rugs all looked great for a few weeks then got the dead, dirty flat look again.
If I had it to do over again, we wouldn't have worn shoes inside the house. We rarely even snacked any place but the kitchen and dining rooms so spills weren't the issue it was tracked in messes.