"That is offensive.", what they are really saying is "In my opinion, that is offensive."
Really, Chas? The aforementioned American in-law went into to a prolonged rant against Blacks and foreigners. Given that my own mother was a foreigner, that we lived in a foreign country and thus were foreigners ourselves, that there are Black people in my extended family and that my father was born in and grew up in an African country, I think I was quite right to feel offended. And I let him know it, too. He slunk away but I'm sure he was unrepentant and unreformed.
The English woman and the South Americans were just as vile, although their targets were different.