After that infamous chiding Eddie Murphy told us about in Raw, one would think Bill Cosby too quick to dismiss comedians just for saying "filth-flarn-filth in-front-of-peeeople." Cosby—who famously avoids profanity, except for one or two brilliant, emphatic uses—clarifies this a little bit in an interview with the Dallas Morning News.
George Carlin is brilliant with words and Johnny Winters is very creative. It's taking something common and drawing out the humor, being clever with words. You take everyday occurrences and look at the lighter side.
Now, Richard Pryor was unique. Many misunderstood his humor. He lit up the hallway, but they didn't understand his use of profanity. He didn't use it just to be using it; he used it in the context of his satire. For instance: In one of his routines, a man wants to be the king of his house, he gets angry and drunk through frustration and takes it out on his wife. Pryor's word choice is in the context of the story, not just to use bad language.
(Via Comedy Central Insider)