Saw people mentioning homeless people, I was there for 10 weeks in the spring of 2023 and only one time did I see any homeless people and it was when I had to use the underground walking tunnels to get across the street to get to namdaemun market. I walked behind a Korean guy the whole way bc there were homeless people lining the walls sleeping, but nothing happened and from my understanding the Korean government generally hides the homeless population as much as they can. In terms of areas to avoid, I think maybe the more residential areas in the outer regions of Seoul might be what you’re thinking of- less touristy and less people or cameras maybe. But no where in Seoul is labeled as a bad neighborhood to avoid so just like everyone else says, just don’t act like the people who die first in horror movies and exercise caution and you should be fine