I know this is only anecdotal evidence, but whenever I do have to go into SF for meetings, it's not a pleasant experience. I do feel for the suffering that is evident in the city. But having to literally step carefully over syringes and flecks of human feces everywhere makes my trips to SF a health hazard. Once I was about to sit down on BART when I noticed a syringe left jabbed into the seat cushion, with blood still visible inside the syringe's barrel. Had I sat down, I may have contracted a blood-borne disease.