The sorting hat seems to think Harry is a pure-blooded wizard.

[davewitley]

No: HPFGUIDX 105769

Jenni wrote:
>   I'm sitting here watching the ABC Family showing of Harry Potter 
and the
> Sorcerer's Stone movie and it suddenly occurred to me that the 
sorting hat
> does seriously consider putting Harry into Slytherin.  

I think you are underestimating the subtlety of the Hat.  It never 
suggested Slytherin.  All it did was start an appraisal of Harry, 
and Harry interrupts with 'Not Slytherin', and the Hat takes him at 
his word without ever committing on what it might have chosen if 
Harry had remained silent.

Later in COS, the Hat still remembers the encounter, and says 'You 
would have done well in Slytherin' - not 'better than in 
Gryffindor', just 'well' - something which Dumbledore effectively 
confirms at the end of the book.

The Hat, as the collective mind of four pioneering educators, is 
doing its job and trying to get Harry to broaden his mind.  It 
focuses on Harry's rather simplistic view of Slytherin and 
challenges it, in a way that, if he thinks about it carefully, both 
endorses the validity of membership of Slytherin and the abilities 
of Harry himself: "Harry, you would do well *anywhere*.  You would 
have done well in Slytherin.  Being in Slytherin would have been 
good for you - but I don't regret putting you in Gryffindor."

David