People can be offended, or claim to be offended, by virtually anything, so some level of common sense needs to be applied. I'd treat this in several categories:
Words that are always considered profanity (typically the 4 letter variety), that all readers immediately know are not suitable for mixed company or young children: never acceptable
Words that are commonly recognized as "hate speech"; highly offensive, derogatory terms referring to groups of people (race, nationality, religion, sexual orientation, handicap, physical attributes, etc.): never acceptable
Words that are commonly recognized as terms that some people find mildly offensive: consider the context (how it is used) and the impact. For example, "bitch".
If someone calls someone else a bitch, it is being used in an insulting and derogatory manner. That's unacceptable.
If it is used as standard English slang in a sentence, that's a different matter, as in: "The connector was a bitch to take off" or "I had a bitch of a time with that error".
There is no reason to search out these cases and prophylactically do anything with them. If someone complains about a specific example:
- If it can be easily edited to use a different word, do it. If it is in a useless comment, delete the comment.
If it can't easily be changed or deletion would be detrimental, leave it alone. Exception: give special consideration to an offending comment on the complainer's own post. In that case, the complainer can't simply go somewhere else to not see it.
If appropriate, thank the complainer for bringing it to our attention and explain that it technically doesn't violate site rules so we ask them to just be tolerant. Other than the exception above, it's a really big site and nothing is forcing them to read that particular post.
Words or language that are not typically recognized as offensive but someone complains about it: Judgement call.
Assess the complainer. Are they just trolling? Ignore the complaint. Does it seem to be a serious complaint but the person is being ridiculously over-sensitive? Maybe explain that it doesn't appear to violate site policy and ask them to clarify what about it they find offensive. If it bothers them enough to respond and they articulate something reasonable, use rules similar to #3 to decide whether to accommodate them.
We want the site to be as friendly as possible, but we also need to weigh the rights of the poster. We should accommodate people's sensibilities when the objections are reasonable and we can easily do it without loss of value to the site or offending someone else. But at some point we need to recognize that some people are special snowflakes who insist on their right to find everything offensive, and accommodating their whims can be offensive to others.
Addendum: It's hard to argue with Ben N's answer. To some degree, we're approaching the question from different angles. For the most part, what we're saying isn't mutually exclusive. The point where the answers diverge is that my answer implies a degree of tolerance for words that are only mildly offensive, while the guidance Ben cites uses as a standard what you would see in a professional, technical publication.
As a simple guideline, that's brilliant. It's a clean way to define a standard that is easily understood and explainable when enforced, and it's consistent with SE's objectives. So let me overlap the two answers.
SU is not a professional, technical publication. That is an atmosphere we would like to emulate, a target. To the extent possible, we want content to be polished, formal, technical discussions, free from "emotional" commentary.
Unfortunately, the majority of contributors aren't practiced at that style. Their objective is either to describe a problem they're experiencing or to help someone else solve one. Writing style is largely an afterthought, if a thought at all.
So cleaning up clearly offensive content is something people should expect. Cleaning up marginally and selectively offensive content is more of a grey area. At some point, it can be stifling on a site that relies on people's unencumbered thought process to get the content onto the site.
We already have contributors who complain when our enthusiastic editors make seemingly trivial grammatical corrections to their posts. Somewhere around half of our audience feels strongly about "free speech" (no limitations on even "unethical" content, let alone word choice--we can talk about piracy as long as we don't use the word "bitch" in the process?).
The "broken window" argument can be made--if we don't allow "bitch" it keeps us farther from discussing whether we should allow piracy. Also,everything we do to polish content contributes to the professional atmosphere we seek.
But too much of a "language police" environment can be detrimental. It's an area that can benefit from a light touch more than heavy-handed enforcement.