It's a matter of zoning: In 1998, when the city's new regulations for adult shops went into effect, the businesses were banned from residential areas. I spent a week trying to figure it all out. More importantly, how do these places, with a clearly dying business model, sustain themselves? And why did they all wind up so close together? The kind that advertise private viewing booths for when the laptop is busted and the WiFi is out and the lock on your bedroom is broken and the bathroom is in use and your imagination is unable to conjure up anything and… you get what I'm getting at. They're sex shops, like the ones you could once find in Times Square. Sunset Video, Video City, Candy Hookah Love, Golden DVD-the names are different, but they're all the same inside. Along on a stretch between 39th and 24th Streets, there are eight of these shops, a rate of nearly one per block. Underneath the Gowanus Expressway, in an area generously included in Sunset Park but really not much more than a detritus-strewn, completely forgotten, and rarely traversed stretch of 3rd Avenue, sit a curious collection of shops, glass windows and brick walls routinely rattled as 18-wheelers hurtle by just 10 feet above.