Taking pictures without a flash is ok, as long as there's no loud clicks and whirrs to distract those around you (they didn't pay a hundred buck a pop to listen to you rustle around).
At the Taboo finale, the announcement actually said "The cast of Taboo kindly requests..." to which the audience applauded loudly.
Cheno's finale was ruined by all the flash photography. Of course curtain calls are fine, but during the quietest moments a flash of light totally distracts everyone's attention.
Don't forget there are people seeing your favorite show for the first time, and they deserve to get the experience they paid for, not "audience participation". Do what you will just be considerate.
"Hey little girls, look at all the men in shiny shirts and no wives!" - Jackie Hoffman, Xanadu, 19 Feb 2008