Most successful confidence men have a very slick line of patter. If you catch them in a lie, they immediately come back with another lie to keep their game going. Quite often, they're excellent actors as well.
Bill Clinton was, like most sociopaths, essentially a con man. And he was a very good one. He knew as much about policy as anyone, could talk circles around just about everybody, and, like all really good con men, could make every single person he met feel that he was his best friend and really cared about him. But as slick as he was, it proved impossible for even him to hide his true nature for long in the goldfish bowl of the presidency.
George W. Bush came across as a bumbler, but he wasn't a con man: what you saw was mostly what you got. Sure, he pretended to be a Texas shit-kicker when he was really an Andover/Yale preppie. And like most upper (or upper middle) class white boys, he tried to come across as tougher than he was. But those are minor, almost normal sorts of affectations. He simply wasn't smart enough, or slick enough, to be smooth and convincing.
Barack Obama ran as a post-racial, post-partisan candidate who was moderately left of center. He said he would hire no lobbyists, allow no earmarks, and run the most transparent administration in history. He disassociated himself from his far left cronies, and managed to fool enough of the American people to get elected. To those familiar with con men, however, "hope" and "change" sounded an awful lot like "snake" and "oil."
A good con man ought to be able to carry his act for a decent interval past election day. Obama couldn't. It quickly became apparent that once he stopped reading from the Teleprompter, he would inevitably say something revealing. The compliant media downplayed it, so most of his gaffes have gone down the memory hole, but his entire Presidency has essentially been one big blooper reel.
Someone ought to compile a highlight reel of his gaffes and put it on Youtube. It would make for very entertaining viewing: Obama saying he'd been to 57 states, with one to go. Obama saying he didn't know how to speak Austrian. His comment about the Cambridge police acting stupidly after Professor Gates was arrested, juxtaposed with his comment three months later that "we shouldn't jump to any conclusions" after Major Hasan's butchery of fourteen soldiers. His speech with the three references to the Marine "Corpse-men." His comment that "they treat me like a dog." Obama speaking from a Teleprompter to a group of sixth graders. The list goes on.
A good con man simply can't afford so many gaffes, otherwise he loses the confidence of his victims.