Your inflight observations about the service quality of AMC charter pax carriers are pretty accurate. Some flights are better than others. I spent 24 hrs on a Tower Air redeployer from Nairobi to Macdill last year and the service quality and aircraft interior on N 616FF did not meet contract specs.
The Commercial Carrier Business Metric on the AMC Homepage is a quarterly snapshot of the AMC carriers' contractually required performance. You have made some pretty accurate inferences about the generalities of the metric. For instance, the QAEs try to ensure that the interiors are clean, etc. The results are reflected as "Go/NoGo". The "Pax Satisfaction" column shows the results of "... survey cards returned. The number returned is a statistically valid sample ... ". We look at the cards to see if there are any new lows in service quality.
I assure you that the surveys do not go into our trash cans. My boss mails the surveys to the individual air carriers, so the carriers reps can throw the forms in their trash cans. We try to cause AMC's carriers to be proactive and do something to reduce the concerns/complaints about AMC Carriers' Service Quality.
And ... AMC is finally about to get rid of the its pax carrier, if only through its bankruptcy; not any AMC action to put it down. Tower Air (until recently) had a retired MAC General available as a consultant and trouble shooter, so who knows what sort of decisions get influenced by that type of arrangement. Senator Oberstarr's wife is now consulting for Tower.
BTW, Devil Dog, not all of us are creampuff consumers. I've been jumping with a theater SOC as a reservist since '95 and with the old 12 SFGA in Chicago for ten years prior.