I lived in San Francisco for 25 years and it has been in a headlong slide into a citywide slum for at least 20 years.
It is, without a doubt, the most physically filthy place I’ve ever seen. It has become an open running sewer...and I grew up two blocks from a steel mill near Pittsburgh, PA, so I know filth when I see it.
Have you been down to the center of the shopping district, Union Square, and seen the "citizens" sleeping next to the wall will urine trails running from their trousers down to the curb? Disgusting.