It’s the dead of San Francisco winter and 46 degrees — 46 degrees! — but that’s not stopping certain hardy residents of the sizable apartment structure at 1214 Polk from opening their windows and drying their laundry au naturale. We’re impressed. 46 degrees in San Francisco, particularly along this gusty urban corridor between Bush and Sutter, feels like autumn in the Yukon. This is the southern edge of Polk’s transitional zone, where it emerges from the sleazy chic of “nitespots” like Vertigo and Blur and slowly crawls toward more prim territory northward up into Russian Hill. The upstairs residences on this block are decidedly ordinary, but there’s a dichotomy at work between, for example, the stained glasswork at O’Reilly’s Holy Grail and the $5 haircuts and $20 facials across the road at the International College of Cosmetology II. Of course, Polk St. has always been known as one of San Francisco’s more diverse business thoroughfares....