"… want to turn..."? Mr. Pilot, it has happened, and for over at least a 2 year period. It is high time we retake that square and indeed the entire downtown area. How about large groups of peaceful citizens with cameras that stand near these folks and record them? The groups could work in shifts. Openly film them. Don't interact, mind you, just film and observe. Do this for a week or two and I think, if the groups are large enough and persistent enough, that the light of observation will remove the blight.