Funny, I'm from the US and find it difficult to understand some of the accents from both North-Eastern Americans (ayy Boston) and some of the UK folks I've met (when they write exactly how they speak).
I'm non-native English speaker and find that I can understand the severely broken pronunciation of people from China or India, but many of the English accents from England are quite impossible. I can ask them to repeat over and over again, and can't understand a thing, and feel rather silly.
I'm a native English speaker with the world's most broadcast accent (the main Hollywood movie accent) and I'm a fan of Sherlock and Doctor Who. Those programs are produced with the most well known UK accents.
And yet I still have to rewind a few times in every episode for dialogue that I just can't decypher. Sometimes I never quite get the words.