For the most part, Google's published ad policy holds few surprises. The banned list includes the obvious such as child porn, illegal drugs and prostitution.

It also is no fan of cable descramblers, gambling and radar jammers.

Google, whose corporate motto is "Do No Evil," also seeks to prevent violence or hate against protected groups as defined by race, gender and age, among others.

The search engine goes one step further by barring any antigroup or anti-individual ads. That might explain why some advertisers who tried to post negative competitive ads were rejected.

https://adwords.google.com/select/contentpolicy.html