TOP: The NBC Bay Area Investigative Unit revisited 20 of the city's dirtiest blocks. BOTTOM LEFT:MIDDLE: NBC Bay Area noted a 39 percent decline in the amount of needles on streets and sidewalks when comparing the November survey results to the prior survey conducted in January. BOTTOM RIGHT:BOTTOM: The NBC Bay Area Investigative Unit spotted feces 159 times on just 20 blocks. Near the entrance to the federal courthouse, on Turk Street near Polk Street, there were 18 feces sightings on just one block.