Just finished demo and ended up with the usual cold water extraction with the scorpion and glided wand!
Dry compound cleaning did nothing. Towelling off Heavy Duty Soil Lifter did nothing but with spray extraction soil did remove to a degree, maybe 50%, there was black gallon of water in the tank after cleaning 6 m. I did try the CFR tool at low psi but it didn't seem to keep the pile much drier than the wand. Only light agitation was allowed to avoid the pile disintegrating.
Where the carpet was still in good condition round the edges, the pile was hardly affected and looked fairly normal after drying. But where the carpet was worn and soiled the pile was left distorted, the individual fibers being bunched up. These areas I had to leave wet so maybe they will improve on drying.
Makes me wonder if a water based pre spray could have been used.
I brushed the pile the way it wanted to go and of course it looked clean and shiny from one direction and not so clean and bright from the other.
The director of the place understood the situation and was fine with this. I advised him that customers should have their carpets dry cleaned regularly before they get dirty.
Might pop my head round the door over next couple of days to see final result
The only other option left is hot solvent extraction, would it improve on the dry compound clean but fall short of the CWE, maybe but pile distortion wouldn't be a problem.