In high school, the Princess had to put a lot of effort into controlling her gag reflex when she spotted a smudge of teacher spit at the top of her test paper. Really, Mrs. Krebs? Was it necessary to put her through that?
But it's not Mrs. Krebs' fault. That's the reality of pet peeves--they're just meaningless actions that can unintentionally land you on someone's hit list. The Princess is aware that every time she pops her elbows in a public place (it happens more than you think), someone standing nearby is out for her blood, and not in an attractive Edward Cullen way.