If you accidentally say something racist without realising it, somebody tells you and you never say it again, then that’s fine. Carrying on saying it while protesting loudly that “you didn’t mean to offend” - not fine.
Not wanting to rehash another recent thread entirely, but along with words which all but the most blinkered/nasty know are always grossly offensive, there are plenty of words that can be offensive or very ordinary, depending on the context.
Who is the arbiter of what is or isn't racist? If I were to order a black coffee (which some sorts have gone on record as having claimed to be intentionally racist) - or point out a rainbow-design hat to a shop assistant next to some plain ones and say "No, I'd like the coloured one, please" - and 'protest' that I didn't mean to offend, because there clearly was never any offence meant or implied, other than that which may be picked up by some woke perpetually-offended person constantly on the look-out for a self-righteous virtue-fight - does that mean it's 'not fine' if I don't curtail my ordinary, commonly-used absolutely-not-racist/sexist/homophobic etc vocabulary to suit the whims of a fantasist who deems it to be so?
In the recent thread, the OP asked if she was wrong to use the word 'queer' in its original context. I added my contributions throughout the thread to the effect of that it's a normal word, which is part of my normal vocabulary, and I mean no intent whatsoever when naturally using it to refer to an object or a situation. I would never use it to refer to a person, as I know it's also used as an insult aimed at homosexuals; and it's not a particularly kind word to use in general of a person, regardless - but I don't see why I should have to restrict my own natural language, when not even addressing or referring to an actual person.
The general consensus was that, by naturally saying to myself "Hmm, that's queer - I'm sure I left my phone here", that somehow made me a terrible homophobe on the offensive. It's bizarre: the word 'fruit' has been used as an insult to homosexuals too, but I don't hear anybody clamouring to condemn somebody commenting on the lovely apples, oranges and bananas they've just bought as intentionally using hate speech.
I was told by people that, because they only knew the relatively modern minority meaning of 'queer' as a slur on somebody's sexual orientation, that clearly meant that I was being provocative and "You know what you're doing, but you crack on with it, eh."
Absolutely yes to words that are only ever (or frequently) used with the clear intention (or effect) of offending, upsetting or wounding; but we need to beware of allowing people to be self-appointed judges of our intentions when they have no right, knowledge nor mandate to do so.
There are people out there who are either fully self-absorbed and entitled or simply activist trolls, who have nothing better to dedicate their lives to than to seek out offence in every single corner and denounce other people for 'deliberately' causing it, whether by commission or omission. They're seeking a fight and, if you capitulate to them, they see that as a clear admission of deliberate guilt and never stop pushing to restrict other people's normal use of language more and more.
Don't misunderstand me: I hate racism (and other negative isms) and I would always do whatever I could to avoid potentially upsetting somebody; but I also dislike professional offence-hunters. No objection whatsoever to raising a concern with or challenging somebody and explaining what they might not have realised (I would certainly do this myself), but we need to guard strongly against people who think that they have a right to single-handedly manipulate universal language used by hundreds of millions of people and tell others that they are indefensibly wrong for thinking, acting or speaking differently from how they themselves do.