Amidst the pushcart vendors selling bacon-wrapped hot-dogs, religious leaders blasting damning sermons over megaphones, and the homeless wandering around the city, there is one San Francisco fixture most people don't know about -- not even the locals. It's not a bridge or a winding street or anything like that: I'm talking about certain folk who roam San Francisco streets. People who can give you the credentials that make your life actually matter.