this isn't offtopic because one of your Pakistani friend said that muslim countries don't have free border despite having good relation, which is true because of threat of islamist terrorist than may cross the border..
but since China and Pakistan is such a best friend, you usually see Pakistani getting same treatment in China as in any other country of the world...and common Chinese, no matter how much friendly on web, feels uncomfortable/safe with a pakistani around just like any normal person
source: my chinese friends