Cartman is a great character and one that, despite being a complete piece of shit of a human, is likable because the stories are better with him around. He’s also a great depiction of certain segments of society - arrogant, envious, greedy, self centered, manipulative, petty, sore loser, whiny, bitchy - which are too dense to realize he’s supposed to be a parody of them and not a role model.