What was wrong with the exit polls

Dick Morris has some very strong words on yesterday's exit polls:

That an exit poll is always right is an axiom of politics. It is easier to assume that a compass is not pointing north than to assume that an exit poll is incorrect. It takes a deliberate act of fraud and bias to get an exit poll wrong. Since the variables of whether or not a person will actually vote are eliminated in exit polling, it is like peeking at the answer before taking the test. But these exit polls were wrong. And the fact that they were so totally, disastrously wrong is a national scandal. There should be a national investigation to unearth the story behind the bias.