I think people in the West are paranoid about skin color because it conjures up discrimination when ever skin color is brought up, so it has a negative overtone. If a guy is dark because he went sunbathing, you can't call him dark?
In VN skin color is more of beauty trait much like lipstick or hairstyle. There is no discrimination undertone. Vietnamese are also blunt in commenting as they feel the other person doesn't take offense over the comment.
I've been following Troy the last few days. Some of his videos about helping people is pretty engrossing, especially the ones from the north, As you can see most people in the north declined the monetary donations even when they are in need. I'm not sure why.