I agree with the Blaise interpretation. I always thought of him as Arabic, but I can see where Italian comes from, too. I'm trying to pry into Blaise more for an upcoming fic, and I think people tend to place him in the typical Slytherin category. (I will restrain myself from rambling on the common stereotyping of houses.) Blaise is NOT in with Umbridge in OotP, and he doesn't really seem to like his mum a lot. He's not Draco's 'groupie' either, and I appriciate it when people make him interesting because he can got a lot of different ways.
Fleur also gets pegged with 'I'm beautiful but brainless.' She was the ONLY woman in the Tri-wizard tournament, people. If Bill likes her, I think that we, as readers, should see that Jo has put a mark of approvement on her, too, in some way. Her conduct in 'Lament of the Pheonix' definately shows she IS NOT the dumb blonde of the series. People typically tend to sympathize more with Hermione and Ginny, so this is why I feel Fleur is given an unfair representation in most stories.
I honestly found Tonks REALLY misrepresented, but fics on her are becoming a lot better. The girl has gut and is not just clumsy and wild. She's not dumb, either, and I don't like it when people make her too girly just because she's now in love with Remus. She tends to take the portrayal of either being really tom-boyish and clumsy or really weepy and weak.
Bella Black, and for that matter, Narcissa Black, tend to get misrepresented, too. Narcissa IS vain, but we saw she has that side that DOES care about Draco. People can forget this in a fic, and she can come across as having shallow motives. Also, Bella is typically cast as the cold killer, and although we know she is slightly psycotic, we also know she has some affection for her sister and her family. How far that extends, we don't know, but some deeper thoughts would be appriciated.