Does JKR sees ambition as a flaw?

[Jim Ferer]

No: HPFGUIDX 99613

Alla: "But, I really, really want to care about Slytherins. If JKR
indeed wants to convey a message that every year one quarter of
Hogwarts first years are marked by Sorting Hat as potential Death
Eaters, I find it silly."

Not necessarily "one quarter." There are no quotas whatsoever to the
Sorting Hat.  If every first year but one was best suited for
Hufflepuff, that's what the Hat would do. Or for any House.  The law
of averages being what it is, that doesn't happen, but we can't assume
anything about the proportions sorted into each House.  Many people,
including me, have speculated that Hufflepuff might have many more
students than other houses, just because there's more average kids
that exceptional ones. Maybe. 

So, I finally come to my question. Putting the "purebloods are better
than muggle-borns" drivel aside, Slytherins are still supposed to be
ambitious. I read on the other list I belong to the speculation that
JKR considers the ambition to be a greatest flaw in person."	

	
I don't think so.  Harry has ambition, "a thirst to prove [himself]"
lots of it, as the Hat said. So does Cedric, with his striving for
excellence, and Hermione. 

JKR does seem to believe ambition has its risks, though, and the Hat
articulates one of them: "Those cunning folk will use any means to
achieve their ends."  To JKR, it's all about *choices,* as she would
have Dumbledore say in CoS.  How does one go about achieving their
ambition? What are you willing to do to get where you want to go? 
What will it do to you?  There's a lot of choices to make on the way,
and JKR think's they're important for who her characters become.

Alla: "Could someone give me any ideas why. I also read somewhere,
maybe even on this lists that for many Brits ambition is not
considered to be a virtue. Is it true?"

I don't know, being a Yank, but you're asking of denying human nature
is a common British characteristic.  I doubt it.

Jim Ferer