Which way would you say that's biased? For or against the Sinti (or who you believe they represent)?
I thought the hate draining out of her even as a child spits at her was touching and awful and real, and showed the depth of personality in the heroine rather than suggesting that the Sinti were so well-liked by the author that even their projectile saliva was more righteous than someone basically innocent whose face life has trodden on.
The fact that the Sinti area is clean just makes them seem worse as oppressors (because they don't have to deal with any of what they're doing to the werewolves).