People who are sensitive to avoid giving offense tend to be cautious in how they refer to groups of people because the polite (or at least inoffensive) ways of doing so keep changing. In the US we are perhaps most familiar with how the terms for Black people have changed over time, with ‘Negro’ and ‘colored’ falling out of favor, though African American is still acceptable. The change from ‘black’ to ‘Black’ is quite recent. This evolution can lead to mockery by right-wingers, especially white cis males, to make fun of this as political correctness run amok. Some even argue that they have the right to use whatever label they want to use, even if it seen as offensive by the targeted group, and that they should just suck it up.

Linguist John McWhorter explains why euphemisms keep changing, using many examples from all areas of life.

What the cognitive psychologist and linguist Steven Pinker has artfully termed ‘the euphemism treadmill’ is not a tic or a stunt. It is an inevitable and, more to the point, healthy process, necessary in view of the eternal gulf between language and opinion. We think of euphemisms as one-time events, where one prissily coins a way of saying something that detracts from something unpleasant about it. That serves perfectly well as a definition of what euphemism is, but misses the point that euphemism tends to require regular renewal. This is because thought changes more slowly than we can change the words for it, and has a way of catching up with our new coinages. Since that is likely eternal, we must accept that we’ll change our terms just like we change our underwear, as a part of linguistic life in a civilised society.

…

Crippled began as a sympathetic term. However, a sad reality of human society is that there are negative associations and even dismissal harboured against those with disabilities. Thus crippled became accreted with those overtones, so to speak, to the point that handicapped was fashioned as a replacement term free from such baggage.

However, because humans stayed human, it was impossible that handicapped would not, over time, become accreted with similar gunk. Enter disabled, which is now long-lived enough that many process it, too, as harbouring shades of abuse, which conditions a replacement such as differently abled. Notably, the International Society for the Rehabilitation of the Disabled later changed its name again to Rehabilitation, International; today, the organisation prefers to be known simply as ‘RI’, bypassing the inconvenience of actual words altogether. The story has been similar for retarded being replaced by cognitively impaired; for welfare, which today is more often referred to as cash assistance; or by the faceless initials of programmes disbursing it, such as TANF (Temporary Assistance for Needy Families).

Opinion can permeate a euphemism to such an extent that it becomes difficult to conceive of how it once sounded. Welfarehome relief. The empathy in that term was soon blunted by associations with the people granted relief, such that older generations will recall home relief practically uttered as a negative epithet by the 1950s and ’60s. Meanwhile, reflect on what a warm, charitable word welfare is at its core, and how much static and bile we must peel away to hear it that way again. Similar is affirmative action a term that 50 years ago resounded with a clean, stalwart clang of high-minded social justice now sounds freighted, sour, vague and tired to many on both sides of the political spectrum. Racial preferences was an attempt at a replacement – and note its similar fate.
…

The euphemism treadmill, then, is neither just a form of bureaucratese, nor of identity politics. It is a symptom of the fact that, however much we would like it to be otherwise, it ís easier to change language than to change thought.
…

This means that, in a linguistically mature society, we should expect that the terms we introduce to help us kick off new ways of thinking will require periodic replacement, like tyres.

Understanding this and accepting it does not mean that the problems go away, though.

I find it best to use whatever term that the members of that group themselves prefer to be referred by even if sometimes it is a little counter-intuitive. One group that I have difficulty with and that McWhorter unfortunately does not discuss is the description for people with the medical condition known as dwarfism. But while the medical term remains, it is offensive to call someone with it a dwarf. Recently, someone in a conversation referred to them as midgets and another person gently pointed out that that term is considered a slur and that the preferred label by the community is Little People. But that term is not universally accepted even within that community, with some preferring the term ‘dwarf’. ‘Little people’ sounds awkward to me too, though that is not my call.

Correcting the use of words by others is a delicate business that most of us shy away from. I was at a meeting of faculty at my university when one of them referred to ‘Oriental’ students. I could see a surprised reaction from others in the room but no one (including me) said anything. A couple of weeks later I was at another meeting when that same faculty member repeated the term. After the meeting, I pulled him aside and gently said that ‘Oriental’ was considered offensive nowadays and not the preferred term and that he should use ‘Asian’ or ‘East Asian’ instead if he wanted to be very specific. He was surprised but thanked me profusely, saying that he had been completely unaware of the negative connotations (he was an immigrant from Europe) and that he would not use it in future.

I had once thought that the term ‘Indian’ for members of indigenous North American tribes was offensive and thus used the term ‘Native American’ instead. But a professor of Native American studies told me that that term was created by academics, and that the preference of Native Americans is to use the specific tribe name such as Sioux or Cree or Navajo. Failing that, the more general term they prefer is ‘Indian’. ‘Native American’, though not viewed as offensive, comes third in preference. I still hesitate to use ‘Indian’ though, since it has been ingrained into me (perhaps by old westerns) that it is faintly derogatory, apart from the confusion it creates with people from India

Most people use negative terms out of ignorance, because they have not kept current, not because of malice. Conversely, members of the targeted groups can usually tell when someone is using a term out of ignorance and not with the intent to hurt and will thus forgive a lapse.