According to Richard Cohen writing in the Washington Post:

I have been particularly harsh on McCain for his irresponsible choice of Sarah Palin as his running mate. I withdraw none of it; the better we got to know Palin, the more egregious a choice she became -- astonishingly unprepared and unsuited for the presidency.  She proves, if anything, that McCain was, too.

But what, then, can we make of Kerry's choice of Edwards?  It is not quite in the Palin category, since Edwards had been in the Senate for one term and had made a career for himself as a stunningly successful trial attorney. Still, not only did he lack legislative achievement, but, in retrospect, it's clear that little was known about him. He dazzled as a political matinee idol -- a profile, a speech, a mirage of a marriage.

The out-of-nowhere rise of Palin and Edwards in less than a decade is warning enough that something is wrong. I will also throw Barack Obama into the mix, not because I know something nefarious about him but because I realize more and more that I know so little about him.

 http://www.washingtonpost.com/wp-dyn/content/article/2010/01/25/AR2010012502833.html