Originally Posted by Bestwifeever
Many of the ads you see are put there by Google based on the sites you've visited--I've never seen the ad you refer to. I have a Nordstrom ad right now--I looked at their site yesterday.
Site owners can ask Google to not show certain types of ads, and this will override the user's history. One of those types is "political". See here
(probably requires a Google AdSense account).
So you can set up your site so that "political" ads will (in theory) never show even if the subject matter is U.S. health care reform, "adult" ads will never show even if the reader is otherwise a pr0n hound, etc.