Most people can cover up their abhorence by pretending to be nice, or squeeze a smile at you and try to be polite, but in the deepmost of their heart, they dislike you or even hate you. That is the majority of people you deem "有的香港人对大陆的很友好" . If they take on a sullen face and give up their bogus smiles, that means they already feel unbearable and can hardly control their bellicose inclination, and that coonsists of most of the people 很不友好 .