Suspension of disbelief? I mean, if I see a Korean person in the street, and they are talking English, I dont look twice. Likewise if they were talking Korean, it wouldn't phase me.
I just see the Korean actors as talking in English. I just dont overthink it, and enjoy the story.
If it was really bad with an actor moving his or her mouth silently for an entire sentence as they animatedly react to something, and then right in the the middle a disinterested English voice just says 'No'... Then yeah, that's total crap...
But it isn't anything remotely even like that, so I enjoy it
