I think you are referring to East Asian men, because, well, have you been to South Asia?
Many South Asian men sport full-grown beards that would put Dumbledore’s attempt at a beard to shame.
Dude, Asia, is big - you have to specify which part of Asia.
I shall assume your question refers to East Asian men, since you mention Koreans.
I’ll let the Koreans speak on Korean men, but for Chinese, it’s super easy to identify which individual is a man, and which one a woman, when both of them sport super smooth, hairless faces.
You just have to know what to look for.
The below individual is a clean-shaven Chinese man.
It’s obvious he’s a man because his forehead is higher, broader, and more protruded due to the shape of his forehead frontal bone.
His cheeks are flatter on the face and are not as full and protruded as his female counterpart’s.
His jaw is larger, broader, more angular, and his chin is more protruded
The below individual is a Chinese woman.
You can see that she has a much softer brow ridge, which gives the forehead a vertical or rounder, smoother appearance. The less pronounced brow ridge also translates to a more open angle between nose and forehead.
Her cheeks are more full and protruded, so when compared to his cheeks, hers look rounder and softer.
Her jaw is also much smaller and forms a V-shape, with a less pronounced definition, thus making it appear softer and rounder.
And if you’re still confused after all that, well, she has breasts, he doesn’t.
Contrary to popular belief, Chinese men do grow facial hair.
Naturally, just how much facial hair depends on the individual.
Someone like me can barely go beyond peach fuzz on the upper lip, even after 2 months of not shaving.
More hirsute Chinese men, like some of my friends, will sport a 5′o'clock shadow if they don’t shave in the morning.
The much more important bit is this:
The vast majority of Chinese women, at least in my experience, prefer their men to be clean shaven.
In my 30+ years of existence on this rocky ball, I have never once heard a Chinese woman mention that she prefers her boyfriend/husband to sport facial hair.
Never.
I have already shared my own experience here on Quora, where I tried to grow my barely-there peach fuzz for Movember, an experiment to see whether it can grow beyond my upper lip (result: it can’t). And after two months of not shaving, my ex-girlfriend gave me the evil eye and basically demanded that I shave all that peach fuzz of lest I continue looking like a destitute homeless vagrant.
The below individual is 胡歌 (Hu Ge) a Chinese actor.
When my sister and mother saw shots of him sporting facial hair, they immediately quipped that he looked like some oily, sleazy-looking Uncle-aged womanizer.
According to them, it wasn’t a good look.
They much (x 1,000,000) preferred his clean-shaven look:
Conclusion a.k.a TLDR:
It’s very easy to differentiate between Chinese men and Chinese women, even when the former are clean shaven.
Many Chinese men - including myself - groom ourselves based on what Chinese women like to see.
In my 30+ years of existence, I have never once heard a Chinese woman say she prefers her boyfriend/husband to sport facial hair.
Therefore, I do not sport facial hair.
I have no intention of making myself look unattractive to Chinese women.
For what should be very obvious reasons.
