These are some of the things I've learned from going to a paid fitness club in Korea:
1) Gyms are friggin' expensive here. But if you're expecting Sports Club LA/Equinox, you will be sorely disappointed.
2) Everyone is so incredibly important that they need to carry their phones around with them while they workout. If a phone call comes in while running on the treadmill, it is imperative to immediately take the call outside, but leave the treadmill operating.
3) Hanging upside down is oddly considered exercise.
4) So is this strange machine with a "belt" that vibrates, but I deliberately chose a gym that didn't have one of those things, in order to reduce the ajumma quotient.
5) Korean men never, ever wash their hands after going to the bathroom. Ever. #1 or #2, doesn't matter. There's soap in the bathroom, but it never has to be replaced because I'm the only one who ever uses it. Remember that, ladies, next time you're holding hands with a Korean guy.
6) Given the obscenely disgusting hygiene fact from above, you might find it surprising that they actually brush their teeth quite a lot. Sometimes immediately after taking a dump and then not washing their hands. I'm not judging. Okay, I am. It's disgusting.
7) Shoe tying is a lost art in the Republic of Korea. Equally rare as hand washing, it seems that no adult Korean person knows how to tie their shoes, at least among men. All shoes exist in a sort of permatie, and are worn like slippers. As a corollary, everyone is very adept with a shoehorn.
8) Back to the gym: female trainers do a much better job training people than male trainers. Especially when it comes to training girls. Male trainers make girls do completely useless exercises.
9) Despite plentiful cultural mores around touching the opposite sex, many of the "exercises" that male trainers in #7 give their female clients are thinly veiled excuses to touch them.
10) I am the only person in my gym, other than the one trainer who's a bodybuilder, who seems to know what the power rack is for, and how to use the safety pins. I did see one other member using the pins once, but they were about mid-abdomen height and used as a sort of trampoline (he had placed mats over them to improve the bounce).
11) When counting reps in Korean, you can shorten some of the two syllable numbers to one (하나, 둘, 셋, 넷, 닷(-엇), 엿(-엇), 일곱, 여덜, 아홉, 열).
12) And back to the locker room: hair dryers seem to only be used for balls. Yep, I said it.
13) In general, people are super nice and polite, and way more chill than American gyms. Never seen a meathead fight. Yet.