They do have a disclaimer at the beginning of the show that says something to the effect that "if you have not been offended, we apologize".
Time is our most precious "gift" and I have never wasted one second of it on South Park.
I know someone who suffers from severe clinical depression. She is also a big "South Park" fan. Watching a favorite episode put her in a better mood and makes her happier than a week's supply of paxil.
If watching "South Park" is therapeutic for a depressed person, it could actually save that person's life.
I've only watched maybe two episodes of South Park since it begun.