Politicians are masters of spin. Watch C-Span to see them in action. From what I've observed, its not about avoiding the question, its avoiding the question enough to not implicate yourself in any negative sense. Bush, ******* though he is, is a case in point. (I) When asked what his mistakes were, he never admitted to making one, (II) he said he'd do Iraq over again, exactly the same way, (III) democracy (this is his viewpoint) will spread from Iraq to the rest of the Middle East, (IV) Iraq still poses a threat to the US, (V) there are no WMDs there (this was the initial justification for the invasion in the first place) but overthrowing an evil guy like Saddam easily overrules that. If you watch Bush giving a speech/answering questions, he'll never swerve from these points. The reality confounds his whole perspective, but you'll never see the man implicate himself. He has ready-made answers, which I think is true of every politician. Bush, in my opinion, is not subtle enough... I don't think he can be, given the magnitude of some of his failures. But I have seen other politicians, when asked how, give replies like, "of course we will fix social security" and then launch into a tirade about the failures of the old system. And do I love it when they end their response with "for the well-being and prosperity of all Americans." Just watch how many times they say "America." Its like a chain-smoker experiencing nicotine withdrawal symptoms.
Sorry for injecting politics into this, couldn't help it. I think the basic point is not to implicate yourself during an interview.