I think we all say things unconsciously that may hurt other people. The other day at a friend's birthday dinner, I made a comment about how my friend was looking really good because he has lost some weight. Well, there is another friend in our group, a girl, who is a larger gal. I realized that while my comment was innocent and meant as a compliment, there was another person in the group who might have been made uncomfortable by the conversation. I quickly changed the subject.
It sucks to have to deal with the daily indignities of life when people point out your acne / scars, but we also have to learn to distinguish between a careless comment and the kind that is clearly meant to be malicious.