How long has Snape been reading Harry's mind?

[oiboyz]

No: HPFGUIDX 134804

>From HBP, p. 154 (Brit edition):

   "Harry wondered whether he could slip his Invisibility Cloak back 
on, thereby gaining his seat at the long Gryffindor table (which, 
inconveniently, was the furthest from the Entrance Hall) without being 
noticed.
   As though he had read Harry's mind, however, Snape said, 'No Cloak.  
You can walk in so that everyone sees you, which is what you wanted, 
I'm sure.'"

   That could've been a lucky guess on Snape's part, but later in HBP 
Snape definitely reads Harry's mind when he asks him where he learned 
the Sectumsepra spell.  In the Occlumency lessons in Book 5, Snape 
seemed to need a wand and the incantation "Legilimens!" for that sort 
of thing, but in HBP he calls up the Potions textbook in Harry's mind 
without any spoken incantation or wand use at all (that I'm aware of).  
Harry can feel the effects-- "the bathroom seemed to shimmer before his 
eyes"-- but what if you don't notice having your mind read unless 
you're expecting it?

   This is likely to make me re-interpret every Snape/Harry interaction 
in the canon.  If Snape can really read Harry's mind as easily as he 
did for Sectumsempra... then surely he'll have been doing it for years 
now.  There have been plenty of times when Snape tried to wring 
confessions out of Harry, and he always seemed to know or suspect 
whenever Harry was lying.  On the other hand, there were times when 
Snape definitely didn't get the information he was seeking.  I 
speculate that he could be under orders from Dumbledore not to use his 
powers against the students; certainly that's one of the first orders 
I'd give if I had a bad-tempered mind-reader on my staff.

   Of course, Harry's probably also a bad liar.  Didn't JKR say that he 
carries his emotions too close to the surface, or something like that, 
and that's why he sucks at Occlumency?

--oiboyz