Viral Marketing and Impact on Box Office

I heard a pretty interesting dialogue on the radio about the impact of viral marketing and word of mouth on movies today. Seems like a year or two back, even a bad movie could manage to stay around and make reasonable box office numbers before the word really got around that the movie is bad. So it had a shelf life of an average of 10days-2 weeks. In this twitter, facebook age of viral marketing, if a movie is not good it takes folks 2-3 hours and they tweet about it and the word spreads. So a bad movie today has an average shelf life of 2 days now. Sure bodes bad news for movie producers. Seems like now its more important than ever to make a good movie. Seems pretty self evident- doesnt it- duhhh!!