My pet peeve would be prejudice against helicopter pilots. We never bother anyone and follow all the rules and yet still get harrassed by club members to the point that other club members start to get embarrassed.
I have actually told some plank fliers(jokingly of course) that they are only allowed to fly in a certain area so that they do not interfere with our flying. To my surprise, they did not like that.
I fly planes too and never have an issue with anyone flying. Heli pilots just get a bum rap like we are out to wreck everything. At one point a fellow club member suggested that the others realize that just one helicopter cost more than two or three fully equipped planes and to take that into consideration before passing judgment.
Needless to say it is a touchy subject at that particular field.