It is not polite to boo in concert halls. It is apparently polite to fall asleep and show other signs of boredom.
I say bah! to that. If you can't get yourself to boo at least get up and walk out at the first available opportunity.
At a nursing home where I used to play with some frequency I recall showing up once early enough to chat with some of the potential audience. They were disappointed that I was not going to play the music they really enjoyed: pop stuff. I told them that if I were good at it I would play it, but I'm not.
Then I made a deal. They should come and listen and, if they didn't like it, leave - but do so in between pieces. I kept track of the departures. None.
It should be assumed that audience will get up and go if you don't hold their attention. The standards might change. I was going to say "would change" but I realize that the definition of listening has been so eroded by constant background music that it may be that people don't know any more what it feels like to really listen.
I think often with gratitude of Lily Tomlin's joke: I had a terrible nightmare the other night. I dreamed that the man who invented Muzak invented something else.
He did: It's what we now call music.
