What causes people to make racist comments?

I like to believe that Don Imus didn’t wake up that day and think, “Hmm! Let me insult some people!” I mean, in this day and age, it should be pretty damn obvious that what he said was completely inappropriate and was only going to get him into trouble. Surely he knew this.

Mel Gibson had the tenuous excuse that he was drunk. What’s Imus’?

Regardless, these things that people are saying in unguarded moments…is this really how they feel? If so, why? And what can be done?