I scored a 6 and I'm usually good at this. I think there are other factors that would help. I would like to see full body shots. There are signs based on the cloths that they were that would help. also, moving images would help, videos.
I can spot a group of Korean woman walking down the street together from a block away, even in Chinatown. There is something about how they act as a group, that helps identify them, the way they interact with each other.