I don't know nor care about Matt's & Trey's political affiliations, but I do see that people need to open their minds a little bit! Our society has taught us to think in "binary" terms -- right & wrong, left & right, yes & no, true & false, guilty & innocent, Democrat & Republican.
Now, someone might say they follow a certain political party, but it's hard to say how many of that party's beliefs that person might have. A good example is Jesse Ventura, currently governor of Minnesota. (That's a state in the U.S. for those of you who might not know that.) He ran under the Reform Party. But, his actions, beliefs, and words have always (at least in his political career) been Libertarian. He even said in an interview once that he was a Libertarian. So, sure he ran for the Reform Party, and I'm sure he believed in a lot of their proposed reforms...
What I'm trying to get at here is that whether Matt and/or Trey say they're Republican or Democrats, or whether they attack one party or the other -- it doesn't *inherently* mean that they are Republicans because they attack Democrats or that they hate Democrats because they attack some liberal views. Furthermore, if they attack some standard liberal views, that doesn't make them necessarily conservatives. In fact, I think we can rule out that they are conservatives based on the existence of South Park.
I do admire and agree with some of the more "serious" points they weave into South Park. However, I think it's pretty silly to attempt to figure out their complete political philosophy based on some jabs they make in an "animated show for adults." ;) We should all be able to make our own opinions on any given topic without people rushing to lump us into categories.
This happens to me all the time. If I say I hate Al Gore, peopel will automatically assume that I'm a Republican. HELL NO! Or if I say that Gore & Bush are both corporate whores, that must mean I support Nader. HELL NO!
I guess the overriding theme of what I'm trying to say is that we should avoid snap judgments and binary thinking. There *are* more than 2 possibilities to most situations.