Exposure is the key to building tolerance.
Which is why segregation, the black only or white only mentality, was destroyed. If segregation was still in schools, buses and restaurants I do not think racist's would ever realize the error of their ways.
Granted there are stubborn fuckers who can never accept positive proof in their face that all human being's are equal. I truly believe the hearts that were changed were changed only because of exposure to black families, culture, music, food and so on.
If something offends someone in your life you change your behavior. If there is nothing offending them, then there is no behavior to change. The word nigga is part of rap and popular culture now. We sing it in songs and we quote it from movies.
Therefore I dub the word nigga, not racist.