I don't know quite why Scientology in particular causes this reaction, but I'm reminded of Bill Hicks words on artists who do adverts:
"Here's the deal, folks. You do a commercial, you're off the artistic roll call forever. End of story. You're another corporate shill, you're another whore at the capitalist gang-bang, and if you do a commercial there's a price on your head, everything you say is suspect and every word that comes out of your mouth is like a turd falling into my drink."
It describes exactly how I feel about Beck now.