"not good liars" does not mean "can tell no lies"; in this case it means "has not had years of professional training and experience in debating/argument tactics and how to manipulate irrational audiences".

You obviously never attended graduate school :)

Heh. I did, actually. :) That's why I added the "irrational audiences" bit; an academic environment does train you to argue and debate effectively, but with other academically-minded, vaguely rational people. Playing politics with a broader audience requires two related skills that communicating in an academic require doesn't require as often or as strongly: communicating with people who have a much larger inferential distance from you (http://wiki.lesswrong.com/wiki/Inferential_distance), and dealing with people who don't subscribe to logic at all.