I've seen it happen, though. I've watched interviews where the interviewer presses for answers and doesn't accept blatant inaccuracies. You know what the interviewee then does? Interrupts, speaks loudly as though loudness = truth, and ignores anything the interviewer says in favor of repeating the same tired "I'm right and you're wrong no matter what you say" lines. What is an interviewer supposed to do in that situation? It's like interviewing a brick wall at that point. And I'm pretty sure that's what Cheney would do- basically refuse to answer questions.
The reason Stewart absolutely roasted Cramer is not just that he exposed facts, but also because Cramer was such a bad interviewee, at least in light of what I said above. He accepted Stewart's accusations, he was contrite, he was a good subject. That's not what you're 'supposed' to do when you're under attack. If he'd acted like every other person under fire acts these days, the interview wouldn't have been so amazingly harsh and open.
I'm thinking that journalists should have the power to dig out the truth from our highest offices, but if those people refuse to participate in the process, who exactly is going to force them?