In combating against bigotry, it is important that we do not become bigots ourselves.
Regarding painful words, it is my position that policies against uttering them (for people without any intent to hurt) must essentially be no more a courtesy to those sensitized against them, because of words with multiple meanings and foreign languages with different meanings, and also because what is taboo on one society may not be taboo in another. Punishing the reasonably ignorant seems to be immoral to me.
Being sensitized to painful words spoken by people who don't mean them seems to me that it needs to be counted not on the person who says them and does not mean them, but on the people who said them and meant them and made people sensitized to them in the first place. It is the continued damage created by bigots, making words that in some situations are necessary to speak (or far too inconvenient to not use) painful to some because of their bigoted use. The rest of us can try to avoid them, but morality-wise, it looks to me more supererogatory for those in a position to do so rather than a moral obligation.