I'm mostly talking about things like opera and musicals, where a good audience will improve the performance tenfold, and a bad audience will almost destroy the production.

Classical concerts are a little different, but there is still an aura from the audience - even if that **** in the fifth row keeps unwrapping his never-to-be-sufficiently-cursed mints.

Sounds like you've been to some really badly done performances - try to go to somewhere with the right accoustics for the music, then tell us what you think.

(If there's feedback, shoot the sound guy. Really!)
_{I'm a lighting guy so I don't care}