I've read other bloggers kvetching about being assailed by crackpot theorists. Physicists are especially hounded by those who have just proved Einstein wrong. I've also gotten contacted by a few people with their own idiosyncratic music theories, but those aren't offensive, because for the most part they aren't trying to disprove any established musical facts, only trying to put together a grand unifying theory or different interpretive theory. And most often I learn something from those attempts, even if I judge the overall effort to be in the wrong direction. But what I do find offensive is a more directly applicable example of too-little-knowledge causing wrongful judging in the world of music: the choir/band/orchestra parent. I've experienced* parents who have decided that their children's impressions of how to run a rehearsal are more valuable than the impressions of the director. While the director may have over 10 years of training and another 10 years of experience as a professional conductor, his/her rehearsal schedule is a waste of time if the 12-18 year-old child has deemed it so. This is the closest musical equivalent to creationists criticizing evolutionary theory or Pat Robertson claiming that Haitians made a deal with the devil. In each case, a few facts are divorced from the all important context so they can be twisted into a different hypothesis. Pat Robertson falsely equates Voodoo spirits with Satan, creationists falsely equate conjectures with essential axioms, and ensemble parents falsely think that five years of ensemble experience makes their child an expert on running rehearsals. I do not deny that there are bad ensemble directors out there. And sometimes the children are correct in their critiques. But I know I would want some serious corroborating evidence before criticizing a conductor, and that is said as a trumpeter who has dealt with "the hand" in many orchestras.
*Fortunately not directed at me, as the last time I conducted an ensemble was 15 years ago, and that was all college students. And I've only had to deal with helicopter parents three times.