Mike Ditka comes from a Ukrainian family and grew up amongst people of various Slavic extraction in western Pennsylvania. He inevitably had friends who were Slovakian, Serbian, Bulgarian, Slovenian, or Czech. He also probably knew some Polish people, whom he and everyone else he grew up around called "Polacks." I know this because my father grew up near Cleveland, the son of a Macedonian, with friends whose parents came to the area from across Eastern Europe—many of whom attended Sunday Mass at the "Polack Church."
This doesn't excuse what Mike Ditka said Sunday morning on ESPN, as one assumes at some point in his life he'd have come to the realization that most of the world considers "Polack" to be a slur. Ditka calling Colts quarterback Dan Orlovsky a Polack wasn't an attack on Orlovsky—indeed, it would seem to have been a term of endearment from one Slav to another, or simply a defense for his hesitance to be too critical. But you can't call a guy a Polack on TV. Ditka's apology, regretfully, was of the "I'm sorry if I offended anyone" variety instead of the more effective and meaningful "I'm sorry I used a word I know offends people" type—but I guess that leaves one more lesson for Coach to learn.