I went to see a Pixies concert in San Francisco years ago, forget which venue, may have been the Fillmore. We ran over to the McD's across the street before the show to grab a bite to eat. After wading through a bunch of homeless, we got our food, sat down to eat, and this homeless dude walks right up to our table and stands there staring at me while I eat. One of my friends lived in the city, and told me that this was their tactic, to stare at you until you give them some food. (We discussed it with him standing there like he wasn't there, he was like a statue.) He ignored all polite and even impolite pleas to get the eff away, until finally, having had enough of my fries, i handed him the rest. He moved off to a table and gobbled them down.
SF really is a beautiful city, but I think it is past time to drop a nuke on it.