NYers wear more black than the average person and that's just a fact, not a stereotype. All you have to do is look around and compare. When I was at the DC gathering, I was black from head to toe and stood out like a little black traffic beacon. But here, I don't think a thing of it.
I don't know why this is, and in fairness, it *is* an exaggeration. We do like color here, no doubt about it. Especially in summer and spring. I would say in general, NYers are definitely more likely to wear a color than a neutral other than black--meaning any color, including pastels, earth tones, and muted hues. I see olive sometimes, but hardly ever beige unless it is heavily supplemented by black. Cream and white come out a little in warm weather, but I don't see white bottoms too much. Fashion week goers and fashionistas in general wear a lot of black, regardless of city.
It's interesting to me to see how cities all over the world have their own individual flavors and styles. Remember Angies post on Zurich? Not a hint of color in sight! I don't know how that develops but it is rather fun to behold.