Personally was shooting at Singapore Arts Festival over the past few days and am rather disturbed by some photographers' behaviour.
Hope these pointers would make this better between photographers and audience ... If you find all this is rubbish, move on.
1) When organiser say no flash, please dont mount your flashes and then try to sneak in a few flashes in between the performance.
2) Watch where ur flashes are pointing, I was blinded by flash myself. You are disturbing not only the performer and also the audience.
3) Do no obstruct the audience view. ie. do not stand right in front of the small little kids sitting in front trying to watch the performance. Sit down with the kids would be a better option.
4) DO NOT walk across the performance area (And I mean right through the center) when the performance is on-going !