DC seems to be one of the worst cities for this. I suspect it's the general demographic in many of the areas (lots of students, recent ex-students, interns, short-term residents with minimal social circles) coupled with miserable weather.

I haven't seen it be as great a problem in SF or Manhattan, but that could be due to the relative distance of universities from the "interesting" parts of these cities. Berkeley does have this problem near Cal but that's to be expected.