Google's wildly successful Adsense program, while a blessing for some, has become a bane for others. In a lawsuit brought on by Geico, the insurance company claimed damages because some of Google's advertisers buy the "Geico" keyword for the specific reason to display insurance-related messages to the viewers.
While Geico claims that this practice infringes on its trademarked company name, I can't see how this holds any water. I suppose if the ads are defamatory or baselessly attack Geico, the company's lawsuit may have some merit, but even then, Geico should pursue such litigations against the original advertisers, not the publisher itself.
The point is that if everyone wanted to use cheap litigation to stop their competitors or detractors, then that could amount to censorship and that would drastically change the advertising landscape. Even Geico may not like that.