I Know... It's The Hood

As I was arriving home from work the other night, I noticed a red light emitting from one of the apartments in my "development." Outside each apartment, there are light fixtures that have the apartment number on it and at night time, the light comes on, so you can see what number each apartment is via the light bulb inside. Well, as I approached the apartment with the strange red glow, I realized that whomever lived there (the local smack dealer and/or user) had a red scarf over the light, thus igniting the blood-like glow. A gentlemen was sitting outside and I don't think he even looked at me. So to myself, I'm thinking, "What does this red light signify?" I've heard of red light districts, which are blocks that have prostitution. But, has my neighborhood (emphasizing 'hood' mind you) turned into a harboring for the whores? Or could it just be drugs? Any ideas?