Snape's ability to spy?

[frumenta]

No: HPFGUIDX 68721

--- In HPforGrownups at yahoogroups.com, "daisyhead_girl" <vmck at u...> 
wrote:
> <snip> 
> I am questioning Snape's real ability to turn double agent.  His 
cover was somewhat 
> blown in PS/SS at the end.  This is shown as Quirrel/Voldemort 
talks to Harry in the 
> room with the mirror of Erised.  Harry essentially finds out that 
Snape was not  
> cursing his broom during the Quidditch match, that it was 
Quirrel.  I cannot quote, as 
> I haven't seen my copy of PS/SS for years (my hubby keeps loaning 
it out).   I seem to 
> recall something about Snape muttering his stupid counter-curse.  
Wouldn't that have 
> been a clear sign that Snape was on the wrong side in Voldemort's 
opinion.  Clearly, 
> any DE worth their salt would have loved to see the kid who 
brought down the Dark 
> Lord get a little back.  
> 
> So, this brings into question his role in OOP.  What is he really 
doing and can he do it 
> convincingly given the fact that Voldemort really knows that he 
pretty much saved 
> Harry on the Quidditch field already?  This may help support the 
vampire theory that I 
> have seen on several occasions.  
> 
> Thanks for a great board!
> 
> Vicki

My guess is that Snape somehow resolved this with Voldemort. How was 
he to know that Quirrel was hiding Voldemort under his turban, 
anyway? As for saving Harry, it would have been his duty to save any 
student, wouldn't it?

I'm hoping JKR will address this at some point because it doesn't 
make much sense with the facts we have so far.