I think whether something is racist or not has to do with intent. If someone had the confederate flag up because they grew up watching the Dukes of Hazard and saw it as a statement that they are rebels, their intent wasn't racist.
If people want to keep the Washington Redskins name because they grew up with it, they aren't being racist.
Calling someone African American is a way of trying to describe someone in a politically correct manner to avoid being racist. The problem is that the very act of pointing out a person's skin color is considered racist by some people. Is it so different than saying "that tall guy" or "that bald guy" or the "dude with the green eyes over there"? In my mind it is only racist if there is derogatory intent.
If someone calls me cracker I'm not offended because I think it just sounds silly, but if someone calls me "white boy" with venom in their voice, it offends me because of the intent.