i slightly agree with you Pap on the southpark comment, though its never actually ruined the show for me. Sure there are times when it seems too preachy but atleast theres still comedy to be found. It's not like the show is nothing but rants about views they disagree with (and by the way, im not saying thats what you think), its still funny and most of the time its done in a way to disguise the preachiness. Most of the time.
The cartoon wars episodes were pretty preachy, and you can just tell that was Matt and Tre getting it off their chest that they despise family guy, but then they acknowledge the fact that they get "preachy and up its own as$ with messages" so i thought it balanced those episodes out fairly well. Then theres episodes like "Stupid Spoiled Whore" where they just have to take 5 minutes out of the episode just to give a morale lecture at the end when they could of just been making more jokes and hinting at the morale lectures.
Then there are times when Matt and Tre speak thru their characters in a positive way, mainly the episode when they kill off Chef. The scene where the town is mourning Chef and Kyle makes his speech is pretty touching. The message there was for all the fans that felt betrayed at Isaac Hayes leaving the show, telling them not to blame him for leaving and just remember the good things he brought to the show. I'm sure many die hard south park fans were mad at that bit of news but Matt and Tre made their voices heard, thru Kyle, that they loved Isaac and respected his decision for leaving the show, even if they thought personally that it was for the wrong reason. Most importantly they wanted the fans to know, and respect, that too.