Let me see if I have you right, you think that only the left does advertiser boycotts? If so, you lead a very sheltered life if you don't believe the right also engages in boycotts, ever hear of Disney, JCP, Target, NFL, Starbucks, Keurig, Nordstrom, Kellog, to name a few, remember The Dixie Chicks?
The right boycotts just as much as the left, but the left uses bogus email, fax and letter campaigns to bolster their boycotts and for some reason advertisers seem to fear the left more.