Yes - heat, agitation, and dwell time do the cleaning work, not water volume. Our process uses all three aggressively while keeping moisture low, which is why the results match hot water extraction without the drying penalty.
Because it stayed wet too long. Carpet that takes days to dry in valley humidity can sour before it finishes - a problem our roughly one-hour dry time removes entirely.
That is wick-back: residue deep in the pad rising up the fibers as carpet dries slowly. Low moisture plus residue-free rinsing is the specific cure.