For the sake of their reputation, if the person is someone I care about I go on by explaining that they will probably never meet a North Korean because they cannot leave their country at the moment, and also to never ask the next Korean person they meet if they are from North or South ever again.
There are some things people say, and the automatic raising of fingers to slant eyes when describing someone as "china", that I still get from people from all over the world. These are things that people get sued over in one part of the US but also things that my little cousins in Buffalo Grove, Illinois don't even know is inappropriate. So what am I supposed to do when someone accuses me that "No... you're not from LA."?
If people are unknowingly racist, does that still make them racist?
The diplomatic side of me says no because it's not even ignorance we're dealing with here - it's just that some people have absolutely no idea. Sure, the lack of interest may be their fault because it's not that hard to find info on the web. But is the lack of exposure their fault? No! Koreans, we must multiply and conquer new lands! Haha... half joking... because I think we've already started doing that albeit incredibly ethnocentrically.
To me this is a chance for me to help people understand my identity as a Korean-American - and also to put people with really inappropriate comments in their place. Please get that "you are so oriental and tiny and cute aww" BS out of my face. The conversation gets so much better when that is out of the way.