The way they gather together TV audiences in the UK usually leaves a lot to be desired. It's often people with little else to do enticed by a free bus there and back and some sandwiches (I know as I've been to quite a few, a youth group I was in had a connection and we got loads of invites).
There was one exception which was a Welsh youth TV thing where they tried for a nightclub atmosphere and we were plied with free drink despite all being around 15, that probably backfired the other way when at least a couple of people threw up on set.
I went as part of the audience on TFI Friday which was a big mid 90s chat and music show. It was a pretty crappy experience (all the people in the 'bar' they showed were cronies of the presenter and the rest were just herded around like sheep).
It did have a good anecdote though because they played a stunt on us while queuing to get in, a busker came along and played a few tunes, as he was disguised we had no idea it was Bruce Dickinson of Iron Maiden. I gave him 50p so 'passed' their test to see who would give anything when they were being serenaded by a top metal star.