The worst "customer" I ever had to deal with was the head of emergency services for a certain Connecticut town. There was a training event at the base and we were expecting emergency management teams from around the state. This guy shows up with three of his colleagues and none of them want to show ID.
I gave the leader my standard stock answer which is, "Everyone from the lowliest Airman to the Adjutant General is required to show ID to get on this base. Why should I treat you any differently?" This guy loses it. He's in the front passenger seat, and decides to jump out and run around to the gate house side, which, by the way, isn't the smartest thing to do at a military TCP.
He ignores our commands to get back in the vehicle (by now one of my co-workers has also come out), and instead draws attention to the full-bird Colonel rank on his shirt and asks us if we know what it means. Since he is not wearing any permutation of any military uniform I've ever seen, I asked him which branch of service he was claiming to represent. Well, none... he never served. He's a Colonel within the rank structure of his town, that's it. I candidly replied, "Your rank means nothing to me."
Oops. Now the guy goes into full meltdown mode, to the point where the other three guys in the vehicle (who have had a deer-in-the-headlights look this entire time) are telling him to calm down and show us his ID. My co-worker, meanwhile, has called in an "immediate assistance required" to security forces, and two of their guys show up. They browbeat our dear Colonel for several minutes, but reluctantly let him on as he was, in fact, on the entry list. Of course they made a big point of telling him that it is borderline illegal to try to use his "Colonel" rank outside his own rank structure, which was at least satisfying to hear.
If I'd had my way he and his crew would have been turned away and put on the debarment list. Anyway, I got lectured by my own supervisor for my candid reply, which I have to admit did nothing to defuse the situation.