For example, last time I was in the movies, it was a dark picture about incest. During the very scene that a daughter was revealed her father has been raping her, some girl in the audience bursted into muted laughter. Later I read from a paper or something that laughter might be a tool for some to cope with the grave feelings like that. But anyway, it ruined the experience for me, I didn't know if her laughter was a commentary at the movie's quality or what.

In general, I don't want to be told what to feel, when to laugh, when to aww. Hearing those audible reactions from fellow audience members kind of conveys the ques to do so to me anyway.