Intent and context matter
This is important. I'm part Romani. I don't think Jimmy Carr is - I think his background is Irish Traveller, which is a distinct group though the two are often confused. I'll admit that his Holocaust joke made me cringe rather than laugh.
There are a whole bunch of internet policewomen (it's always women) going around saying that you can't say gypsy, it's equivalent to the n-word. I would guess that none of these people are Roma themselves. If they were they'd know that there are serious slurs out there, and the community has much bigger problems to worry about than Jimmy Carr.
There are a lot of working class white Brits out there who might be uncouth and use outdated language and even share an offensive meme sometimes, but who aren't hateful and wouldn't think of treating people poorly because of their ethnicity. Those are people you can have a conversation with and say, you know, we don't say that any more.
The way you can tell serious racists is that they never bloody shut up about it.
I've know a few people in recent years who have become unironic antisemites. They've gone out blazing with righteous indigation, aiming to prove that their hero Jeremy Corbyn is a nice man incapable of prejudice, and three or four months later they're tweeting manically about Zionist control of the UK government.
These are not working class people. They're graduates with nice middle class jobs, who know the right vocabulary to keep them just the right side of being cancelled. They scrub up well, which is why useless regime mouthpieces like James O'Brien or Lewis Goodall aren't thinking of them when they hold forth about racism.