We’re all sensitive about something; all’s fine and dandy until someone pushes that button. It might be something innocuous to nearly everyone else – and may take many forms – but when we encounter it, things turn sour. It repulses us.
When we’re talking to groups, obviously we’re not going to know what those things are and we might (thus) unwittingly say or describe something that makes someone’s stomach turn. I don’t think we can be faulted, if it is not commonly referred to as offensive per se. I think we can usually be forgiven for accidentally offending someone.
In more intimate communication, of course, it’s far easier to tell if what we say or do offends someone – we see the small shudder, or the facial expression. We then usually apologize and/or seek clarification. Most of us who are not total jerks try to avoid offending people personally.
In terms of offensive language, I think some terms, like the n-word, obviously should never be uttered regardless of circumstance, and the majority of people here in the US would agree with that assessment. That word needs to die.
That level of mass revulsion – it doesn’t matter if you are talking to an audience of 1 or 1000, white or black or brown or yellow or red, or a mixture of all of them – needs to be respected. Such terms should be stricken from use by everyone.
Terms like “Feminazi” I think are mostly used sarcastically. If someone is truly offended – personally affected – by it, I have yet to meet one. It doesn’t mean such people do not exist, of course. But I can’t imagine it being reviled to any degree approaching the aforementioned pejorative term.
“Master” is likely not offensive the vast majority of the time, given the circumstances in which it is usually used. Certainly now and then someone might be offended by it, but en masse? I think most would want to take context into account: if we’re in a wheat field in Georgia, talking about plowing or whatever, that might not be an appropriate place to use that term, regardless of who is present. But at a Yale dorm? In no way would most people consider that term offensive under that circumstance. To make it so, you’d have to bring the “19th century Georgia field” mentality into it, and that has no sensible place at modern-day Yale, right?
If 75% of people expressed offense at its use, obviously those who would otherwise use “master” would not use it in order to avoid offending so many people. But clearly it is not that unpopular, so… I think we should take context into account and, like I said, a master at Yale has probably never been the type of master who would cause the term to be offensive. One would have to make a leap of abstraction to make it offensive, IMO, and/or project a personal fear or aversion – or experience, I suppose – onto it.