Imagine that one of your neighbors keeps seeing campaign ads sharply
attacking current environmental regulations, another sees ads
passionately arguing for stronger environmental regulations and the
campaign ads you see never mention the environment.
Now imagine that all these ads come from the same candidate.
This can't happen on TV -- but it's business as usual on the Internet.
-- Jon Peha. "Making political ads personal"
Politico (Sep 11, 2012)
http://www.politico.com/news/stories/0912/81022.html