The word foreigners isn't a dirty word.
It's when it's said with the intent of ostracising a group of people for no valid reason that it becomes a problem.
I have a thick yorkshire accent, and some people, especially foreigners can't understand what I am saying.
In fact, I got in trouble at work once, where an African customer called, they thought they'd found a way to game our system, and I set them straight and explained why the loophole they thought they'd found wouldn't work.
They said "Oh, so I couldn't do that then?
and I said, "No, you cunt"
If you've got a thick Yorkshire accent like me, then you'll know I wasn't calling her a cunt. I was saying no you couldn't.
She complained about me to head office, this then went to our overseas quality assurance team for reviewing, who also agreed that I had called her a cunt, and sent back to my manager who was from down south, who also thought they'd heard me call her a cunt, but agreed in the context of the call, where I was being nothing but polite, that it didn't make sense, yet I still had to go through the disciplinary procedure because of my accent and natural way of speaking.
So I think it's more than fair to say that our accents can be hard for people to understand, especially foreigners who might not have as much experience with the plethora of dialects across the UK and how they differ in such extreme ways.