Living in one of the worse parts of San Francisco, for the past few years (west SOMA), I can say that people going through your trash is quite a nuisance.
You'll put your trash out for pickup day, and a significant portion of the time, someone will come and go through it. And often as they are going through it, they will just throw random things on the ground. So our little side street kind of has a constant layer of trash.
The city does employ people to come through and pick it up, and they do that regularly, but they would have to do it daily to really keep the street clean. I think they come more like weekly.
Tangentially, I was walking my dog this morning, and had to ensure she didn't step on the used hypodermic needle on the sidewalk. Nothing covering the needle. This happens all the time.
Right now they are at least 3 tents on my small side street block.
For businesses, like if you were at an In-n-out you must have been at Fishermans wharf, that's the only one in SF. They regularly have to ask people to leave who are acting in various disruptive ways, and bothering their customers.
A few years back, I was sitting at a bar in SF, that had outdoor tables. I think I was on a first (and only) date. I guy walked up, took my dates glass of white wine, drank the whole thing down, and then said "I'm an alcoholic". And then just stood there looking at us.
(Also as someone who's lived in San Francisco for years, I just can't help but be triggered when someone says San Fran.)