It really is area specific, and I think that is on purpose. When there was the superbowl in SF, all of a sudden certain BART stations stopped smelling like piss and homeless population in those areas were not there any more. Tell me where the homeless camps are around the marina or other wealthy neighborhoods of SF with high foot traffic. Suspiciously missing or hard to find...

Since it's done on purpose, if SF wanted to actually revitalize their downtown they would lay down the law on their mainline tunnel transit stations, caltrain stations, ferry stations, tourist hotel hot spots and market st like they lay down the law in the marina with it's crazy high foot traffic. Yes it is 'moving the problem around', but at least it makes people feel safe and not nauseated where they enter and exit from SF. I bet one good chunk of why people are not coming back to offices to SF is because the transit safety and cleanliness experience is not good there.