It's always been difficult to identify the real loonies. Now cell phone headsets are so innocuous you might not be able to see them. Somebody with long dark hair and a dark shirt or coat might seem to be talking to themselves, but if you look real closely you might see the thin black wire dangling from their ear to a clip on their front before disappearing into a pocket. But who knows if it's really on? Maybe he is just talking to himself. Dummy cell-phone headsets would give the San Francisco street schizos a whole new credibility.