I live in SF. I consider myself very liberal. I know it's not the political orthodox for people on the left, but I will say, it is bad. It is very bad. You learn to live with it, but it's far worse than any other city i've ever lived in.
I think it's a direct result of a complete and utter lack of real estate development, but the fact of the matter is people shit in the street here, regularly. People shoot up heroin openly here. Needles littered on the streets here is normal. People smoke meth and crack, openly.
If you don't want to see it, you can avoid it with a car, but i bike and take transit.
The tenderloin is drug dealers and junkies. 16th and Mission is mentally ill people. Haight is crustypunks. Besides that, there are more normal things like people in tents in parks and under the highways.
I've seen things more like this in places on the west coast, but i've never seen the type of open and welcome drug dependency except in this region. I definitely am supportive of giving addicts a way to get help or even use in a healthy, non-threatening setting that is safe and separated from the rest of us going about our lives, but that's not what's happening.