Acceptable Abuses?

[karenoc1]

No: HPFGUIDX 95695

I don't understand about this one Dumbledore incongruity (I apologize 
if this has been previously discussed!).  I'm wondering why 
Dumbledore allows his students to be abused at all, and I guess I'm 
thinking specifically about Snape.

We know, of course, that Dumbledore was angered about 
Umbridge "manhandling" Marietta Edgecombe.  And we suspect that he 
would have been greatly angered if he knew about Harry (and Lee 
Jordan, I think) suffering physical abuse in detention with 
Umbridge.  But where does Dumbledore stand on emotional abuse?

Here, I'm thinking mainly of the episode in PoA, when Neville could 
not get his (shrinking?) potion to work properly.  Snape gave Neville 
time to fix it before administering it to Trevor, and we all know 
that Trevor did not die because of Hermione's aid to Neville.  But 
Snape fully intended to administer what we can only assume to be 
poison to Neville's pet.  I know that this scene is a device to 
demonstrate why Snape would be Neville's worse fear during the 
boggart lesson, but why does Dumbledore allow a teacher to terrorize 
a student so viciously?

There are also other abuses, like the crack Snape made about 
Hermione's teeth in GoF and the occasions where he purposely 
sabotaged Harry's work just to give him poor grades.

Is it any wonder that Harry is *amazed* that Dumbledore trusts Snape 
implicitly, the teacher who abuses Hogwarts students so pleasurably?  
After all, Dumbedore is supposed to know about everything that 
happens at Hogwarts, right?

Thanks for your thoughts!
karenoc1