We've never had a hose/fitting problem that did enough damage to require carpet replacement, but we once replaced a sisal that a tech "didn't recognize as sisal" and another that had soil wicking that the tech kept trying to bleach out using an oxidizer.
No instances of replacement that I've heard of due to someone just applying the wrong product. I haven't been able to strip fluorochemical from carpet on purpose. I'd be interested to know how it can be done.
PS: Examples of problems leading to carpet replacement based on first-hand observation from long ago inspections:
#1) - Color loss. Usually due to use of oxidizers/brighteners/boosters. Cleaner would (usually unsuccessfully) blame the chemical manufacturer, the carpet manufacturer, the sun, high traffic, cooking oils, fume fading, phases of the moon...
#2) - Agitation and pH damage to wool fiber. Usually done by in-house staff, but sometimes by professional cleaners.
#3) - Yellowing from optical brighteners. Cleaner might have had a shot at including the chemical manufacturer in sharing the cost of replacement.
Prochem had this problem with the original Dry Slurry.
#4) - Yellowing from UV inhibitors. Applicators were pretty responsible about paying for replacement.
#5) - Rapid soil attraction from silicone applied over fluorochemically treated carpet. Applicators were pretty responsible about paying for replacement.
Overwetting was very common, but didn't require an inspection to determine who paid for the replacement.
