Why black? Anyone of any race can look down at another for just being different. It's not that they're trying to be disrespectful, they just find it strange. For example, if you saw a man painted in purple walking around in nothing but a towel and sandals, what would you think?
Maybe you'd tell him to put some clothes on, maybe you'd tell him he looks like an idiot. And what if he tells you it's HIS culture and he can express his beliefs any way he pleases. Of course, you'd still think he's strange, what this person considers normal another might find strange. And of course by you I don't mean you. Just trying to make sense here XP
And people DO tend to stare when they see something out of the norms. They're curious and they'll stare. They don't mean to be rude. As Humans we tend to be very curious about certain things. That's all.
But again, the "especially blacks." was uncalled for. There's no need to mention a race in this question. Is skin color an excuse for how you behave? I think it's more likely the environment or parenting that makes people open minded/close minded about things, not the color.