This is going to sound awful but here goes.

We had tickets for a matinee session to see 'Wicked' a few years back and behind us were seated about a dozen down syndrome teenagers. To say they were noisy and disruptive during the whole show is putting it mildy..to the extent a man at the end of our row eventually turned around and snarled at the two carers to do their damn jobs and shut them up.
Several people in our row said loudly 'hear hear'. For the next 10 minutes all we could hear was the carers going 'shhhh' and the teenagers going 'shhhh' as well! it was worse than before!

The concert was totally spoilt for us and we just left. I never did get to see the show properly.