Depends on the Asians. I find the ones that have been here a couple of generations to be very well mannered, almost courtly. The ones that are fresh off the boat, tend to be a bit lacking. They can be a bit pushy, and sometimes a bit easy going in terms of hygiene. Things like littering, spitting, etc..... don't seem to be frowned upon as much.
My friend that is Chinese attributes this to the fast paced life style in many of those countries, they just don't consider it that big a deal.