Americans like to describe every neighborhood that isn’t predominantly white upper middle class as dangerous. SFBA is predominantly super safe.
Lots of petty crime (vandalism, car breakins etc). Interpersonal crime is largely limited to the hoi polloi with statistically extremely rare instances of things happening to people like us.
If you’re a woman you get a lot of catcalling and other things that make you feel unsafe, but super rare for anything to happen.
As in every large city: avoid groups of young guys, especially if they look like they’ve been drinking. Be careful around people tweaking out on drugs or generally looking like they’re detached from reality or angry at the world
Ultimately don't trust americans who say something is dangerous. They think any neighborhood that contains non-rich brow people is super dangerous and scary.
I guess one problem with USA is that a lot of gang violence is done with guns. If they miss their target and you happen to be anywhere in teh general vicinity behindn the target, you will get shot.
So unlike in Europe where you just gotta cross the street or whatever if you see some shit going down, that won't necessarily save you in US