A lot of areas in DC used to be rough public housing projects back in the 80's.
When those projects were demolished, nice new buildings and homes were built but due to DC Government regulations, low income residents had to be allowed back into the neighborhoods so this caused a mixture of "riff-raff" & "working class" residents.
That's why DC has a lot of nice looking ghettos.
Not to talk down on low-income residents but a high percentage of them don't appreciate nice properties, due to the fact that government pays up to 80% of their rent & they don't have a high amount to pay out of their own pockets.
Look at this article for example:
SE neighborhood's violent past clouds new residents' future - washingtonpost.com
There are a lot of great up & coming DC neighborhoods, but I would check out their past first.