I was in Seoul for a few days.
Managed to check out the anma scene.
For HK chinese, every single anma I visited, accepted us.
So no issues with asian looking foreigners.
Typical price is around 250k won a pop.
The places I visited (if you google them, you'll find the locations):
Castle Anma - 3 girls open play - followed by 1 girl service in a room + normal massage - pretty good. the girl called Rose is quite pretty and very skilled.
Gain Anma - single girl open play then enter room - can see others in the act + normal massage. quite a few pretty girls here. I saw one called Laura, looks a bit like IU, if that is your type.
City Anma - chose an option that had 1 girl for 30 mins, followed by massage, followed by 2nd girl for 30 mins. 2nd girl looked a bit like Yoona from SNSD. can't remember her name though. 2nd girl prettier than the first. again pretty good experience.
Pearl Anma - 1 on 1 with a single girl in a room. no open play + normal massage. was given a choice of pics by the manager, although the faces are blurred. i just asked for the prettiest one and what i got was probably a 7 face, but amazing body.
Overall, Seoul is accessible for asian looking foreigners. Basic english is fine to get by.
Get a hotel in the Seollung area and you'll be pretty close to the anma scene.

answering some questions:
open play means you are playing out in the open in front of other punters as well. some of the doors are just glass doors so you can see inside and there's stools which you can sit on outside and peer inside. certainly not for the shy type. positively you get to scope out the other girls at the establishment and can try and find out their names and book them next time.
FS is included as standard. OWO, etc.
No korean at all. I just said I'm Hong Kong Chinese and they were perfectly fine for all establishments I visited. Foreigner tax did apply to my white friend though. He had to pay an extra 30k. He also got refused a few places as well, which I didn't.
Unfortunately, you don't get to choose the girls. There's no lineup. No pictures. You can tell them your type like i like pretty, young, slim, etc, but it's quite pot luck what you get unless you know a person to book.
The girls in general are typically at least a 6+. Korean girls also are taller and tends to have better bodies than other asian nations given their height.