accents...
I agreee with whoever said that the hardest accents to get a handle on were Glaswegians!!
Back home in Oz we have become used to everyone being able to speak and understand English, even our own idiomatic English (which BTW not many other English speakers understand).
However, in the rest of the world (it's a fairly large place too...) accents and understanding are barriers to communication that must be overcome, how? Standard phrasiology..no other way. I show my trainees here in the Middle East how easy it is to use them, then try the next China Southern (or Russian, or whatever) with non standard phrasiology...result? Chaos, but a good learning tool.
the standard phrasiologies are there for a very good reason.
BTW, none of the guys that I work with (except for about half the expats) have English as a first language....yet they all manage quite well, you just get used to it!
cheers