Secret Agent Snape

[subrosax99]

No: HPFGUIDX 76839

I just did a quick re-read of GoF, and something caught my eye that I 
missed the first time. At Karkaroff's hearing (or whatever that was), 
Karkaroff gives out the names of several people that he knows to be 
DE's. One of the names was, of course, Snape. Then Dumbledore says 
something to the effect of "Snape is no longer a DE, he turned spy 
for us at great personal risk." Obviously Karkaroff heard this. 
Wouldn't he have turned around and shared that information with his 
fellow DE's in Azkaban?
Though I don't recall Karkaroff being mentioned in OoP, it's safe to 
assume he's still on the loose. What if he uses his information about 
Snape to save himself from LV?
On top of this, wasn't it kind of stupid for Dumbledore to mention 
the fact that Snape was a spy in front of Karkaroff? 
Sorry if this has all been mentioned before. (And I'm sure it must 
have been.)

Allyson