I have one and it is awesome. 2-3 Complete carpet clean should clear out all the crap. The water coming out is like greyish so it is pretty efficient.
I bought it three weeks ago when Argos is doing like half price. Not sure how the AAA fluid works but it cleared up bad smell from my carpet
However I have to note that the detachable handheld unit on my Vax cleaner is quite crap TBH.
P.S. I live in college hall which is 3 years old and the previous occupants don't give a damn about the room, and the hall don't actually have the equipment to clean the carpet. And the vacuum cleaner (no beater bar) is utterly useless...
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