I believe that most posters specifying nationality do so because where there are similar social/cultural behaviours and expectations that it makes it easier to cohabitate.

Sorry, I wouldn't want someone in my shared living space who felt it was OK to spit, hawk up various bodily fluids or scratch various body parts in the shared spaces of the house. I wouldn't want to take on the task of re-training an adult on what I felt comfortable with. I would look for someone whose mother had already trained them properly from my social perspective.