DD got a new Rainbow floor cleaning system. She takes after her paternal grandmother, who is a little OCD and her maternal grandfather, who comes from German stock (things must be clean in a house for both of them).
The demonstrator used her vacuum cleaner to clean the carpet - then used the Rainbow.
Which clearly pulled even more gunk out of the carpet than her previous machine (Kirby) had.
I vacuumed a couple of times while I stayed with them and did some spot cleaning with the steam cleaner attachments. There was a lot of tiny bits of sand, gravel, pet hair, cat whiskers, muddy dust, and I don't know what else pulled out of the carpet (they bought the house in 2007 and have been living in it for seven years - she does tend to vacuum but not nearly as often as "Grandma" - who used to vacuum twice a day because she didn't like footprints in the carpet, they didn't look clean with footprints).
Grandma is now 80 and the house is vacuumed a couple of times a week instead of a couple of times a day...
I made sure to clean the tank immediately as it sets up as an air purifier to get airborne dust out of the way - allergies run in the family, too, not just tendencies to OCD. I did not need any allergy meds as long as I stayed inside the house for five weeks...
Having a clear plastic tank that you can see into does make it very clear that the tank needs to be emptied. My own Bissell is inside two layers of green plastic and the used steam cleaning mix cannot be seen at all. But if you don't empty it, you can smell it fairly quickly...Houston is warm and things grow quickly...