How's Snape Doing it?

[lizvega2]

No: HPFGUIDX 89521

Pg. 591- OOP US Edition:


"...It is not up to you to find out what the Dark Lord is saying to 
his Death Eaters."

"No- that's your job, isn't it?" Harry shot at him. 

....

"Yes, Potter," he said, his eyes glinting. "That is my job. Now, if 
you are ready, we will start agin..."

I've always wondered how exactly Snape was spying on Voldemort when 
we know that he has the capability of knowing when someone is lying 
to 
him. I came across an interesting theory: Snape is using polyjuice 
potion containing Barty Crouch jr.'s hair. The proof:

Barty wasn't killed. He was given the dementor's kiss. Victims of 
the kiss are still alive, but comatose. His hair would still be 
usable. 

Voldemort doesn't know what happened to Barty Crouch, jr. The last 
thing he knew was Harry touched the port key, and was gone from the 
graveyard. Snape left the hospital ward, 'prepared'a little while 
later, to do what? If he was going to spy, which the above quote in 
my estimation confirms this, wouldn't it be easier to return to 
Voldemort as Barty jr., than Snape?

Barty, who did everything VL told him to, including getting Harry 
through the Tri-Wizard Tournament, no easy feat by his own 
admission. VL referred to Barty as his faithful servant, he probably 
wouldn't be probing the feelings of Barty as heavily as Snape. 

Can anyone tell me if there's any referance to the public, or even 
the students at Hogwarts finding out the Barty was masquerading as 
Moody?