As much as many people complain about "hurp a durrrp fart jokes" and other such poor attempts to bitch about the fantastic humour of South Park, they are very good at it.
South Park has layers and layers of subtlety, most missed by the audience. But many of the political or ethical episodes, while brutal and dark in pulling it off, are very deep. It works for both audiences. Those who like "dem fart jokes" and those who find it very witty.
Even down to what characters are doing in the background of a crowd or parts of a crowd rolling their eyes, almost missed if you didn't know about it, add to it.