Wait, wait! I've heard of this... it's called a... a... a disguise?

That disguise comes with make-up.
Some do, some don't.
Become a stage 4 vampire, then your skin colour does not change with makeup from disguises.

I dunno, if I were the sneaky type and didn't want to be recognized, I'd add some makeup in addition to the garments...
Perfectly plausible and it's used in a quest in Auridon. Turns any race into a buttugly altmer with no scalp and a huge beard.
Personally I'm fine with it, as long as it all comes off when the disguise is removed.

I have the same issue on my argonian but i have realized they only black or blue.
One of my characters is a blue argonian and whenever i switch to my black argonians sometimes they change color to blue.

He has never been changed to a different color so i was thinking its some sort of bug that loads wrong class properties from other characters like color of my argonian characters.