By Jim Emerson Editor, RogerEbert.com October 14, 2004Who's the, uh, biggest villain in "Team America"? Kim Jong Il or Hollywood celebrities?"You should learn to keep your opinions OUT of your reviews!" Every critic I know has received at least one letter like that from an indignant reader. Of course, it's an absurd proposition; critics are paid to express their opinions, and the good ones (who exercise what is known across all disciplines as "critical thinking") are also able to cite examples and employ sound reasoning to build an argument, showing you how and why they reached their verdict. Well, since...