With the stand-up comic on TV, whether it's Seinfeld or Cosby or Roseanne, more important than their knowledge of how to tell a joke is their knowledge of themselves, or the persona they've created as themselves. So that when you're in a room with writers, you can say, 'Guys, that's a funny line, but I wouldn't say it.'
I remember seeing a movie with Jose Ferrer and Rosemary Clooney where they were husband and wife, and they got in bed, and he had on polka-dot pajamas and she had on striped pajamas, and when they got up the next morning he had on the striped pajamas and she had the polka dot pajamas, and that was considered racy at that time!