In Umbridge's lesson, when she mentions Moody, Dean Thomas reacts by saying that "afterwards it turned out he was insane" (or some such, don't have the English version). I had been wondering at the end of book four how much Dumbledore had told the students about what had been going on. Now we find out, to some extent anyway. Are we to take it that the students still believe it was Moody teaching them, and were merely told that Moody had finally cracked and gone insane? Smart move by Dumbledore to not mention to the public that he failed to distinguish Moody from his Death Eater impersonator, I suppose. But is this really a big cover-up with Moody's reputation (what was left of it) as the price?

If that's really what the students were told, it's no wonder none of the students trust Harry or can make heads or tails of the whole incident: they haven't had any explication for the Portkey, any indication of how Harry and Cedric got to Voldemort and when they returned one of the two was dead. How are they going to gainsay the version of the Prophet or the rumours that their parents discuss, if they don't know the truth themselves other than Dumbledore's word that Voldemort killed Cedric?

In hindsight, you have to ask yourself why Dumbledore didn't tell his students and the world the *full* truth. Who is he protecting by covering up Barty Crouch Junior's role? Is it just a matter of avoiding open confrontation with the Ministry by the frontal attack on Fudge that he'd be forced to make about BCJ's death? And considering that the Ministry ends up being hostile to him anyway, wouldn't that have been preferable?