I only hear ignorant, uneducated blacks use the word to greet someone or they are trying to be cool. I am black and I do not use the N word in my everyday conversations. Also, the older generation of blacks hate that word! My grandparents don't get it and they would slap me if I used the N word to greet another black person. It's just the younger generation of blacks that use it a lot.
I think the user David gets it. It's like you wouldn't allow someone outside your family to insult you. I hear white people call each other derogatory names, like honkey, but I wouldn't call them that because I'm not white. I feel like they can say that to each other because they're both from the same race. It would just sound awkward if I said it.
Anyway, no one should have the "desire" to use a racial slur.