I've visited it as a tourist many times, and have walked around extensively in neighborhoods such as Nob Hill, Fisherman's Wharf, Union Square, Financial District, and Inner/Outer Richmond. Never stepped on human shit, much less dog shit.
The city has, over the past decades, slowly taken over all public seating in homeless-prone areas of the city. It's a sunny day outside and you want to have a seat and munch on a sandwich instead of eating at your desk? No can do, there are literally no seats, benches, or anything that might be remotely comfortable to rest on.
Ditto public restrooms, which have been taken away under the same pretenses.
Of course, the response hasn't been a decrease in homelessness - they lean, lie, and sit against buildings just fine, and they piss and shit in the streets just as well too.
San Francisco's stance towards homelessness seems to be "if we make it inconvenient to be homeless, people will stop being homeless", which strikes me as shockingly idiotic for a city famous for its liberalism.
I was volunteering for an "alleyway beautification" project in downtown, and it just turned out that there was a small, cute park adjacent to the alley. To our dismay though, we found it to be locked 24/7. When we asked the city officials, they said it got locked because the homeless were using it as their living space!
Similarly, when the cops are dealing with homeless people with mental disorders, do you know what they do? They don't actually take them to the station to write them up - they learned long ago that doing so doesn't accomplish anything (the system is not equipped to deal with mental disorders, especially in people with no money).
Instead, they sit them in the backseat of their patrol car, drive them over to one of the adjacent cities (i.e. San Pedro, Carson, etc.) and drop them off there. That way, those homeless become that other city's problem!
Can you believe it?
It's crazy. I feel really bad making this analogy, but it's like sweeping the trash under the carpet and pretending the room is clean.
http://upload.wikimedia.org/wikipedia/commons/6/6c/RIVER_ROU...
It's gotten better, but it's not exactly a residential city:
http://upload.wikimedia.org/wikipedia/commons/4/4f/ZugIsland...
When I visit family, the I-75 bridge over River Rouge is a windows-up, vent-closed affair. River Rouge is rather famous these days for annoying Canada with hums, too.
Most startup types here commute to SoMa, and, well...
