Over past few weeks, BP has been targeting many oil spill related search terms, including "oil spill". Recently, over at WebmasterWorld, it was noticed that the "display URL" in BP's "oil spill" AdWords ad didn't match the "link URL", thus, violating Google guidelines — in particular, "a rule that requires showing people the site they'll be going to when clicking on an ad."
A Google spokesperson said that "Our Display URL policy for AdWords text ads requires that an ad's display URL match its destination URL. In this case, due to a combination of human and system error, the mismatch wasn't flagged. The error is being corrected."
Here's BP's oil spill ad:
Notice the URL www.BP.com/OilSpillClean, according to Google AdWords display URL policy, when the ad is clicked, it should take you to cited "URL ony". Instead, the ad lead over to BP's YouTube channel: