Places outside the USA haven't had as strict of a racial divide and so yeah I can see how it would get muddled.

Yes, although it's also all these secondary things, I'm guessing there was an implication in your comment that speaking Spanish was a sign someone had Central or South American heritage/etc. and was therefore non-white, whereas in other countries the main people speaking Spanish and Portuguese were from Europe so that isn't a signal in the culture.

You mentioned Dominican people, and I think this generalizes to many other countries with European colonialism history without much diverse post-WW European immigration (contrast: USA, Australia) and they retained a strict racial divide as a result. An interesting counter-case is a memetic documentary clip filmed during an uprising in Tanganyika (basically now Tanzania) where the filmmakers are dragged out of their car and approaching a wall to be shot, when a soldier sees their passports and says "these aren’t whites, they’re Italians". My (naïve!) guess is that their understanding of white stems from their British and Belgian oppression, and possibly even shaped by around a hundred thousand Tanganyikans fighting for the Allied forces in WWII.

Bashar al-Assad is an excellent test, because most people in the West envision Middle Eastern people as inherently having darker skin, certainly not light skin and blue eyes which are primary traits racist whites boast about. There's a strong dissonance there, the same kind that makes dumbass neo-nazis start obsessing about poorly guessing who is Jewish or not. The point being, people assume they can tell, and often get it wrong, as you've shown.