Look in the mirror. All your mentioned negative characteristics fit perfectly to chinese tourists.
The reason why chinese tourists are so "rude" is because of the living conditions in 70's. Most chinese tourists are 40+. A time when china was a back water 3rd world country(from the economic standpoint not political) where they had to work hard all day and manners where not a priority. Due to the middle class boom they want see new things and go to other countries. But they never had the time to learn manners so the don't behave properly in more developed countries.