Adams Morgan, Monday night, 11 p.m.: An earth-tone-clad, dreadlocked, 30-something black man carrying a shoulder bag is having trouble hailing a cab. Frustrated, he beings to walk down 18th Street toward a quartet of bike cops standing in front of the Madam’s Organ bar. “Hey,” he says. “Help a brother out.” In seconds the cops respond, waving down the first empty cab. Man and shoulder bag disappear into the cab and roll on into the night.