There are times in cricket when a stump mic picks up some exchange of words between bowler and batsman that wouldn't bother anyone, but because it's broadcast it causes such a who-ha that disciplinary action follows. In football I wouldn't want every overheard expletive to lead to some similar punishment. I'm a bit torn between having it recorded but only 'dipped into' as and when a broadcaster thinks it's worthwhile, and using the rest for ex post facto investigations, or having the mic open all the time and, as has been said above, put pressure on players AND refs to grow up a bit.