The LA Weekly article "No Politics, Please, We're American." Here's the money-left-wing-transglobal-progressive bleat:

It hasn't always been this way. Political activism in Hollywood dates back to the 1930s, when many entertainers and writers threw themselves into studio-unionization drives and celebrity-signatured fund-raisers for Republican Spain. The moviegoing public paid little attention to these enthusiasms, but such activities offended some powerful conservatives in government and media - men who quietly bided their time until, after WWII, they had enough clout to lash out with witch-hunts and blacklists. Suddenly people in Hollywood were seen if not as sinister ideologues then as starry-eyed, susceptible dupes whose politics could never be taken seriously.

Conspiracy, paranoia, it's all in the LA Weekly.