I used to live in a small town served by TW Express (CMI) and traveled on TWA quite a bit, connecting in STL. I was red card, so I could call 72 hours in advance and confirm an upgrade seat by phone. I checked in for my entire outbound in CMI and about 80% of the time, the gate agent would "forget" to take my upgrade certs. Now they did know me there... I don't know if they were really forgetting, or they were conveniently "forgetting" :-).

Once I made the mistake of "checking in" again in the Amb club in STL during a layover and the agent had a conniption about my next boarding pass not having upgrade certs. She said that she was going to report CMI... I was worried, but the practice didn't change :-).