FWIW if you search "tenderloin city" the answer appears immediately.
It's a big internet, sometimes people will mention neighborhoods or customs you're unfamiliar with. In my experience, the polite thing is usually to take 3s to make the Google.
This is the problem with context and language and assumptions and algorithms. Even with that I get two restaurants and one Wikipedia article on meat before I get anything resembling a city district in my search results.
In my experience the polite thing is to just say “San Francisco” instead of talking down to people.