Interesting thread! I've never left a show at intermission, in the last decade or so I have been going to the theatre. And I can't say I've noticed anyone doing so. However, I don't go to shows I have a feeling I'll probably dislike, and I'd rather see a show I like more than once, as opposed to just seeing a show I don't know. And I rarely take reviews into consideration. Usually, a performer or a theme brings you to the show and, regardless of opinion, I'll go see it just for the performer or that particular show.