My observations from Opgani have been that Hyugetels are mostly Thai and Gunmas are almost always Korean. The only exception to Thai Hyugetels are the One Shops, which are mostly Korean.
The prices also run much different. For the Koreans, the options are basic (or not told up front) and consist of something around 90,000 for massage / handplay, 130,000 for massage / VIP (FS I assume). For the Thai girls, it's wide open and upfront. 80,000 for 30 minutes one shot, 130,000 for 60 minutes, multiple shots, as many shots as you want, BBFS, BBFSCIP, anal, dildoes, whatever you want. It's pretty obvious the difference between the two.
I haven't tested it yet, but I'm willing to bet that it's usually the Thai providers that are going to be pimped out to foreign customers versus the Korean girls who will shut you off from the start. Just my thoughts, will be interesting to hear if Bon Jovi or another has a similar experience.