Advertising does work, but it also has other issues being overlooked. For instance, all Geico commercials featuring the Cave Men have made me hate listening to Royksopp. I don't believe that's an effect Geico or Royksopp could have anticipated. Be ready for the affects good or bad if you're the 3rd party in one of these 'viral' ads.
Whenever a catchy "indie" tune hits the top of Spotify, I wonder just how long it has before it becomes a VW commercial or the ending credits of The Hills.