Not related to this particular problem. About a year ago I had to call C4's duty office because a programme had very thin, odd sound. Thinking it sounded like phase reversal I put the telly into mono, and lo and behold the sound dissappeared altogether! It WAS being transmitted out of phase. Needless to say the guy on the phone didn't have a clue what I was talking about. I did, however, ask him to pass the information on to an engineer. A couple of minutes later the sound miraculously got better!
It's not just C4 either. Quite often I'm watching a programme with an ongoing fault on it , thinking to myself is anyone actually monitoring the output?!