San Francisco -- surprise! -- has surpassed Los Angeles as the capital of the gay adult entertainment industry. To the list of accolades that make San Francisco the gayest city around, you can add this: world headquarters of the gay adult entertainment industry. Over the past few years the core of that industry has shifted from Los Angeles to San Francisco, and nearly every leading studio that makes gay adult content now is centered in the city, mainly in the South of Market and lower Potrero Hill neighborhoods. The content of the industry -- that is, the movies themselves --...