[Kluny]

> I've lived all over the country and doubt the poor neighborhoods in Chicago (where I'm from) and Detroit (where I once lived) do their respective cities much good from an investment point of view (whatever that means).

Well, check the data, don't just "doubt it". It means that neighborhoods on the bad side of town tend to generate enough tax revenue to pay for their road, electric, and sewer maintenance, whereas neighborhoods on the good side of town tend not to.