It has some good examples, for example the one about a journalist exposing corruption in high places but who has a secret (like drug abuse in the example). She could be attacked for this secret in order to discredit her exposé on a totally unrelated matter. I think everyone has secrets of some kind, but even if you are not a journalist, you want journalists like this to exist and be free to conduct their investigations. This is why the argument that "you shouldn't be afraid if you have nothing to hide" is bogus.
http://martinfowler.com/articles/bothersome-privacy.html