Question for Mr. Fish

I was mainly curious where you pull the subject matter from. You have such an array of religious and controversial topics portrayed in your work. My main question however, is how one knows when a political cartoon has crossed that fine line from being hilarious to hurtful. Being that you are a well known political cartoonist it will be interesting to get your views on how much is too much when creating a satirical version of another person. Also, does this vary based on the impression, personality and popularity of a person?