Mexican dude here as well. The last time I visited SF I was assaulted by some random dirty homeless drug addict: I was waiting my wife outside of a Sephora near Market Street drinking some bottled water, when suddenly a huge dude (I'm a small Mexican, 1.67m) stands extremely close to my side and starts shouting shit to me. I could not understand what he was saying, and it was evident he was disturbed. After about a minute of him shouting at me I got to grasp something about "water", I guessed that he wanted my bottle of water, so I gave it to him and walked to the Sephora shop.

It reminded me of here in Mexico, because all people passing by were just getting away from both of us, and nobody did anything.

I haven't returned to SF and don't plan to return if I can prevent it.