Looks are critical to account for in engineering a physical con... in a way that minimizes the chances of someone undesirably thinking twice about your actions.
I don't know. Charisma and looks are pretty much orthogonal, at least for some people. The canonical example is Hitler, somebody whom you'd think people would instinctively avoid at work or the neighborhood bar, yet who somehow ended up running Germany.
It never hurts to be hot or handsome -- would a young Donald Trump who looked and sounded like Hitler have gotten very far in life? -- but it clearly isn't an absolute requirement.