I agree and disagree with skib upto a point in that most of the sketches in the critique section are 'mainstream'. But that is because most people are mainstream, that is their frame of reference. Laughter is a spontaneous physical reaction to a shock or surprize - be it emotional, physical or intellectual. Usually this surprize is a pleasant one. The problem with 'dark' material is that you shock some of your audience into disgust rather than joy.
I disagree in that I think there are some genuinely funny people who make me laugh out loud. Niteowl, winterlight, charley and a few others are consistantly funny in my opinion.
What I am trying to say is that I am a brave prude, but not that brave! (I know, you had a lucky escape yada yada.)
All the best for 08!