Music
Music questions in quizbowl focus largely on the Western concert music repertoire, or what a layperson might call "classical music". Opera questions which focus on plot clues and aria names are not considered music questions, nor are questions on ballet or jazz, though those feature prominently in the Other Arts category. Questions on pop, rock music, metal, etc. are never acceptable topics for fine arts questions, and are always written as trash.
Because of the extremes difference in depth of knowledge between people with music theory education and knowledge of the concert repertory and those who do not, music is often considered one of, if not the, most difficult category/ies to write good questions in for a general audience.
See Music mafia.