The Kony 2012 thing was an unfortunate case of an otherwise very admirable cause (motivating Ugandan authorities to capture Joseph Kony) being dragged down by the media's attention on the personal failings of its adherents (the fact that some of the charity money was probably used for bribes, and the masturbation thing).
It was really kind of stupid to watch. On the first day, everyone's talking about Kony and how he really should be caught. On the second day, everyone's gossiping about the fact that the guy who made the video was a fundamentalist Christian or whatever, and a month later he's caught masturbating in public and then that's all everybody talks about, and we're not paying attention to the guy who enslaves children to use as cannon fodder and prostitutes.
He is literally worse than the bad guy from Far Cry 3, and he actually exists, and somehow we forgot that because we're all headline-addicted scandal whores.
Anyway. I would say the Kony 2012, but I can give a regional example and point to the Australian federal government's hung parliament, which was heralded by several commenters in 2010 as bringing the possibility for discussion of more diverse policy issues into the federal arena. Everyone was talking about how this was going to revitalise Australian political discussion.
Unfortunately, the prime minister has the charisma of a 2x4 and the leader of the opposition is only good at making other people look worse than he is, so instead 2012 was a year of some of the most trivial, unnecessary, irrelevant, sometimes wildly illogical political shit-throwing that I have ever seen from an army of monkeys in expensive suits.