Having once worked in reservations prior to customer service, I can assure you if someone is a real jerk we put notes in the PNR. Thinks like..
Mr/Ms so-and-so was advised such-and-such
(rules, changes, penalties, fees etc)
at least xxx times and was nasty and irate, was given to a supervisor for further clarification etc....The outcome is then noted by the supvr in the PNR.
I felt this was a courtesy to the next agent that had to deal with this thick-headed moron who was going to call back a hundred times until he/she got the answer THEY wanted.
The only drawback is if such a moron is rude enough to lean over and look onto the computer at the ticket counter or gate and see the remarks - this might (but not likely) get the reservationist in trouble for putting in the remarks.
In any case, he/she moron is extremely rude and out of line for stepping into space they don't belong in (on the other side of the counter/gate)