Spot on about Brit ex pats sadly. I had locals asking if I was Italian or German because I was holding up my end of a conversation making an effort, get my pronunciation at least semi comprehensible and generally to speak and learn Spanish. Sad commentary on Brits abroad.
And yes I have had those convos with foreigners living here, the few Russians I've met are particularly know it all.
Whether or not Afghanistan, Iraq was a good idea, even at the time you'd have thought that we were invading Sweden and not a dictatorship the way people were talking and still talk.
It doesn't occur to a lot of these people that the reason they are so clued up on the myriad crimes of the British is that a certain sort of Brit has gone out of their way to tell the world about it. Usually shorn of context or comparison.
If only there was some sort of institution to educate people about history...
With "BAME" types I generally don't go there and keep to small talk... although my "Indian" friend (he's from Ealing, grew up in Kenya and sounds super posh anyway) I do occasionally put right on his misconceptions on The Raj, Partition etc.
It's ironic that people come here and slag off Britain so much, despite this country being much better than others. And yes, we have the best manners.