The idea of the scene, by the way, is that the villains are secretly meeting under cover of the opera. They are scattered through the audience and communicating with radio microphones and earpieces. Now... is it just me, or does that seem a bit unlikely? Wouldn't the whole audience turn round to look at a villain every time he spoke into his radio?
It varies, IRF. In my experience talking is likely to attract stares and shushing in productions of Wagner, Richard Strauss, Janacek, Berg etc. These are operas I'm more likely to attend but on the rare occasions when I've seen something by Mozart, Rossini, Bellini, Johann Strauss etc I've noticed that such behaviour (which is, imo, extremely ignorant and rude) tends to be tolerated. There also seem to be different norms in different locations. Talking during the performance seems to be less common in German, Dutch & English houses than in French (and, I've heard, Italian) ones. These comments are based entirely on my limited experience - I've never been to an Italian or Austrian House - but it's interesting that I've never heard chattering at Gent Opera House but never failed to notice it at La Monnaie in Brussels. And all three of my visits to Paris houses (Bastille & Châtelet, I've never been to the Garnier house) have, to a greater or lesser extent, been blighted by such behaviour.
Your villains, who would, presumably, be a hard-faced lot, would probably get away with it. Even if they attracted attention and disapproval it's unlikely anyone would actually do anything. If people refuse to behave there's little that can be done without causing a bigger disturbance than the one you're trying to prevent; and most people won't want to do that.
