[simondotau]

Absolutely not. All cities have rougher areas, because cities need workers that are only paid enough to live in affordable hosing and affordable housing inevitably clumps together.

But it doesn't automatically follow that a rough area is "bad" in the way it is in San Francisco. Plenty of cities in Australia, for example, have their share of upmarket and downmarket suburbs. But the lesser suburbs are rarely dangerous and their poor reputation is largely socio-economic, relativistic and/or historical prejudice.