SAN FRANCISCO - An effort to clean up some of the city's seedier neighborhoods and rid the streets of junkies, hookers and runaways has run headlong into San Francisco's free-to-be-who-you-are ethos. Nearly four decades after the Summer of Love, residents and merchants frustrated with what they regard as blight are turning to the city for help or taking revitalization into their own hands. But other residents of the Tenderloin district and Haight-Ashbury contend a crackdown would rob their neighborhoods of their identity and violate everything San Francisco stands for. Joey Cain, a board member of the Haight-Ashbury Neighborhood Council, complained...