Whoaoaoaooaaaaoooo......
Taking a big step backwards here, and should clarify some more.
The "bugging" of lapel Mic's is only done for a few seconds, to make sure that we're getting good signal from the wireless Mic's. It's a very quick run from Channel 1 through to Channel 18 to make sure that there's actually signal happening.
As for sitting there deliberately, we only ever do that with our somewhat bipolar Techie Actors, who flip from one side of the curtain to the other with every new performance, this is because they are VERY aware of the fact that we're listening. In response to KMC, Scoot and BalletPSM, Yes, we quite often hear these particular actors 'badmouthing' us, but all parties are aware that it's in jest.
I'm by no means condoning the practice of eavesdropping on Mic'ed actors for sinister purposes, but I do maintain (in argument with scoot) that is is "a bit of fun". I would never dream of eavesdropping with actors and crew that I was unfamiliar with, because of the reasons that have been posted here.
I should also point out that the configuration of the theatre where most of this goes on is Black Box. During a show, the actors can see myself and anyone else on a console VERY clearly - ergo, during rehearsals and setup, actors know we're up there, and most of the time are shouting conversations with us anyway.
Chill out, let's avoid the flame war. I agree that everything has its time and place.