I'm a "quick study." I can, working from a superficial base of knowledge, read through pages of new material, and go out and give a presentation on it the next day as if I were an expert, and fool pretty much everyone who isn't an expert. I've done this many times, and I think lots of people can do it, given the proper training, practice, and motivation. What I can't do is learn a bunch of new material on several different subjects, subjects which are largely alien to me, then go out and give a presentation on it and work my way through a hostile Q&A session, all while making sure my words conform to a worldview that I either don't understand, or disagree with. Nobody's that quick a study, at least not that I've ever seen. I imagine if I tried to do that, I would look pretty damn foolish as I tripped over talking points, repeated myself, and tried to think my way through questions that an expert, even a near-expert, would answer off the cuff.
Of course, that's exactly the point of all this, isn't it? That Palin either doesn't have the base of knowledge that anyone in her position should have, or lacks the intellectual juice to learn quickly enough to fake it (maybe it's both??) has got to be frightening to everyone at this point, or at least everyone who would put "country first."