Like other truly talented phonies, Barack Obama concentrates his skills on the effect of his words on other people — most of whom do not have the time to become knowledgeable about the things he is talking about. Whether what he says bears any relationship to the facts is politically irrelevant.
A talented con man, or a slick politician, does not waste his time trying to convince knowledgeable skeptics. His job is to keep the true believers believing. He is not going to convince the others anyway.