LA
Hollywood sighting

It seemed more like a stereotype of the American south. The house Tracy lived in itself was a "sh** hole" as Evie Zamora put it. It was like something out of The Texas Chainsaw Massecre (dirty, old junk everywhere, cheap paper flooring, chicken farm, etc). The main characters looked, acted and sounded like stereotypical rednecks. They were like characters that Rob Zombie would write.
I live in Los Angeles and people don't typically live like redneck/white trash stereotypes here.

I currently live near Philadelphia and have never been to California but I think there are definitely suburban neighborhoods like that near most major cities. California in general has one of the highest costs of living in the United States but the median income tends to be higher as well. The cost of housing does vary quite a bit across the USA and sometimes even varies quite a bit between different neighborhoods in the same metropolitan area.
In Thirteen, it was implied that Tracy's father had a pretty good-paying job and her mother presumably got the house when they got divorced. And even so, Tracy's mother certainly seemed to be having money problems (she mentioned having to have an average of 12 hairdressing clients haircuts per day and Tracy complained about always having "store brand" food and not being able to afford new clothes).