We get a fair number of PA people at the library. I tend to either ignore their comments entirely or accept them completely at face value. In some ways it helps that I seem to be having minor hearing trouble. I really don't hear some comments that aren't directed straight at me, so I don't even have to lie about that.
We had one guy a month or so ago that I'm reminded of for some reason. I don't think I've mentioned him before. He'd been a recurring problem for awhile, but never enough to trigger an official reaction. He's a little slow mentally but plenty smart enough to use "Oh, I didn't know that" or "I forgot" in his favor. He's also very large and quite happy to loom over people until they do what he wants. He gets frustrated easily with the computers when they don't run as quickly as he thinks they should, or do exactly what he wants. I'm pretty sure his ideas of how computers should work come straight off of TV or out of the movies, so needless to say real computers seldom measure up.
One day he was in an especially bad mood with the computers because they were "too slow." No, they weren't, but try telling him that. He took to picking up the monitor and banging it against the desk hard enough that he actually knocked loose some wires underneath the computer desks. The librarian told him in no uncertain terms not to treat the computers that way, and he snarled "Fine!" and stomped into the main room. Then the librarian had to get down on her hands and knees to restore service to the two or three people whose computers this guy had messed up.
I didn't know any of this at the time. I just saw this guy stomping up to the desk in a bad mood. He flourished his library card at me and said, "I want to cancel my account! Just delete me from the system!" He pretty obviously expected to be fawned over and convinced to stay part of our wonderful library system.
I just said, "Okay," and used his card to call up his record and delete it. If he'd had books checked out or owed fines I couldn't have done it so easily, but he only ever used his card to access the internet, so it took me about ten seconds. I then threw his card into the trash and said, "You're all set. Your record has been deleted."
It took him a minute, but he came back with, "... Oh. Okay. I guess I'll just sign up again later if I want to."
"That sounds like a plan. Is there anything else I can help you with?"
No, there wasn't, and he walked out. We haven't seen him since. The librarian thanked me profusely.