When I did the article on Paula Jones and the Curse of Ham, I promised something on Investigative Reporting. In fact, I have received a couple of e-mail letters from people who dislike sensationalism, but at the same time hate to see public figures "getting away with murder" (and other crimes). Since then I read G.K. Chesterton's Heretics which has a great chapter on the difference between sensationalism and the kind of exposť which could truly be called bold. I quote the opening sentences of that chapter and encourage you to read the whole book. (It is available on-line by clicking the link above.)
VIII. The Mildness of the Yellow Press
There is a great deal of protest made from one quarter or another nowadays against the influence of that new journalism which is associated with the names of Sir Alfred Harmsworth and Mr. Pearson. But almost everybody who attacks it attacks on the ground that it is very sensational, very violent and vulgar and startling. I am speaking in no affected contrariety, but in the simplicity of a genuine personal impression, when I say that this journalism offends as being not sensational or violent enough. The real vice is not that it is startling, but that it is quite insupportably tame. The whole object is to keep carefully along a certain level of the expected and the commonplace; it may be low, but it must take care also to be flat...