Over the last three days, I've spent 12 hours trying to clean roughly 100 square feet of 6 month old carpet after my dog tracked in a bit of mud. The room is a home office that otherwise sees a 5 foot stretch from the entrance to my office chair on occasion. Little to no other activity in the room. It's vacuumed with a $1k+ top of the line vacuum weekly.
I will say, the machine does a fine job of pulling ground in dirt out of the carpet, but the MAJOR problem is it does a horrendous job of picking all that up in the dirty water it creates. Conjecture here, but the fill line on the dirty water tank is roughly half the capacity of the clean water tank, so I figure this is something the manufacturer expects. Pretty hard to get a carpet clean when you're leaving half the mess behind, every single time. I'd equate it to covering your hands in mud, splashing a bit of soapy water on the mix, and calling that clean.
Over the last few days, I've ran this cleaner over every inch of this seldom-used home office space, and I'm still left with brown waste water. I counted at least 15 back and forth wet passes (countless dry passes) in every section, with some having more. Out of curiosity, I even went to 40 wet passes in one section and you guessed it, still brown waste water. I filled a total of 18 gallons with 3 different types of cleaners, all the while using the deep clean mode to no avail. I'd figured maybe the brown water was a fluke the first night, as this was my first experience with the product. However, the next morning when the carpet dried I was greeted with the strongest wet-dog smell you could possibly imagine. I literally could not focus enough to work and had to take time off to attempt to re-clean the carpet. I tried again with a different cleaner and the wet dog smell subsided for the most part until you got down next to the carpet after it had dried the next time. We're talking my nose a foot or so away. Also though, if you touched the carpet with your hand, the smell would transfer. The carpet never had a smell before using this machine. I attribute this smell to what is left behind by the product during the cleaning process. I tried again a third time in the hope the water would finally come out clean and the smell finally gone, but still no luck. After 18 gallons of water being used, it stands to reason there's now 9 gallons of dirty water left in my carpet.
If anyone's curious, following manufacturer instructions for deep clean (ex: 1 or 2 dry passes depending on cleaner solution used), moisture reading is 43%. If you go over the carpet again and again and again, and add weight to the nose of the product as other reviewers have mentioned they've done to increase suction, moisture reading still only improves to 38%. Do what you will with that info.
As for me, I'm returning this to my place of purchase and I will likely never buy a Bissell product again, especially after seeing the canned responses to others with this and similar issues in poor reviews throughout the web.