Hayes Valley is just west of City Hall and Civic Center in San Francisco. I have lived here, very happily, for two years. The shop owners know me by first name. Many residents are artists. Hayes Valley is also home to trendy boutiques, bohemian bars and swanky cafes. Just four blocks long, it is like a small and eclectic artist village. But what the tourist books won’t tell you is that Hayes Valley is also fraught with tension.