Why is theatre such a dirty word in politics?

guardian.co.uk: From comments reported in the New York Times describing deposed Egyptian leader Hosni Mubarak's trial as "just another element of political theatre", to the FT's account of the "political theatre" of Rupert and James Murdoch's recent appearance before the culture, media and sport select committee, it seems that "theatre" is the word which tells us that someone is trying to pull the wool over our eyes, and that what we are watching is rhetorical, empty and all for show. Is this fair?