I live in Mexico City and we have a large Korean community here. Many are expats living in Mexico for only a year or two. They play a lot of golf and most public golf courses in the area are always packed with Korean players. This has been my experience:
Caddies don't like them. They are rude. I have heard this in many courses. In contrast, caddies say Japanese players are very nice and polite.
Four times out of five Korean groups will NOT let me pass through, even though I'm playing alone. When I politely ask them to let me pass, they just wave their hands at me saying no.
They take a lot of time to play. They bet a lot and they will pay the bets at every hole!!!
When I have been paired up with a Korean group, most times they will not have a conversation with me.
I took the time and effort to learn to say "thank you" in Korean (it sounds something like kamsa amnida), I know I pronounce it well, but when I say it to korean players they don't say anything back, like you are welcome. Only once did a korean player say kamsa amnida to me, but this was a gentleman who had been living here twenty years and obviously had good manners.
I have a mexican friend who works for LG in Mexico. About a year ago I asked her how to say "please" and "thank you" in Korean, and she said I don't know, they never say please or thank you. True story.
I don't think they are bad people. I feel sorry for them, it seems that's just their culture.
It probably is the their culture, and thus their culture is shit. I certainly don't feel bad for them. Joining a private club has been the best decision I've ever made for golf. We don't have to deal with this problem at all.