I hope I'm not alone in thinking it ridiculous that David Petraeus has resigned as head of the CIA because he had an extra-marital affair. That's between him and his wife and family.
It doesn't matter whether he was good or bad at his job, since the 'rule' would apply to the good as well as the bad, and could apply to any organisation or post.
Nor does it say much about the suitability of his character for the high post he occupied, if that is the reason. John F. Kennedy was himself an adulterer, Winston Churchill a drunkard and Adolf Hitler a teetotal vegetarian who wept to music and couldn't abide cruelty to animals (and in that sense he was a man whose time has come, a modern role model if ever there was one).
That Petraeus had it off with his biographer might make people want to read the book with care, but it's not as if he was popping over to Iran to call on Mrs Ahmadinejad and leaving his papers in the wardrobe, is it?
Meanwhile, there is no doubt tumult everywhere in Langley, Virginia, and you don't have to love the CIA to see the danger of following the principle elsewhere.
It's just daft.