We paid a fortune for Phantom tickets and had the misfortune to sit behind a Greek family. The teens clearly lost interest quickly as they were on their phones. Really annoying.
This weekend, at the Empire, they put several announcements out to the audience that singing, talking and heckling in the performance was not allowed and there would be a chance to sing along at the end. After the interval (and, I'm sure, linked to additional alcohol consumption) there was a bit of shushing going on from someone. The reply from the noisy party was to noisily shush back about 5 times - all while the actors were still acting, until one bloke loudly told them to shut up, which they thankfully did.
I've been at the empire and narrowly missed a punch up because people were annoyed that they'd paid a lot and had the show ruined by others.