Pity poor Dr. Mehmet Oz. He gets big bucks hosting the popular Opra Winfrey-syndicated “The Dr. Oz Show” on TV. But now he’s come under fire in Congress, in the media, and on the Internet for promoting health supplements that sold big due to his effusive recommendations -- products now considered by many to be largely useless. How did he respond?With a technique we’ve seen used all too often by governments that indulge in questionable or reprehensible behavior, or by weasely politicians doing something sleazy and trying to reap benefits but not face consequences: by trying to use “plausible deniability.”