Sometimes I will make negative comments about the people I come into contact with daily and since I live in a large city the majority of the people are minorities.
For instance, if I am talking to a friend about a tenant I ran into during the day I will say something like, "... and this stupid mexican waited an entire week before telling management that his toilet was broke." I don't consider that racist, since the person I am talking about is, in fact, mexican. I'm not implying all mexican's are stupid.
Or, you might catch me talking about "all the black people on the corner selling crack" which is common on my block in the city. I don't mean all black people sell crack, but if you walked down my street you will see a lot of black people selling crack so, again, it is just a fact.
Now, if someone wanted to talk about me and say "hey, that irish kid is a moron" I wouldn't take offense to the fact he called me irish, since I am (the moron part is another story). If he called me a mic or a paddy, then I would be mad since it's a derogatory statement to all irishmen.