Since I have seen on a couple of occasions American pilots who could not understand each other - and also when British ones were involved - I'm totally delivered of any feeling of guilt.
Problem is that a lot of those "native-English speakers" are also the ones with the less education, and strange as it might appear, they often have a limited vocabulary or grammar, so totally missing some points - and therefore blaming the other guy for the misunderstanding...
A colleague from Down South was obviously understanding "free gate " instead of " frigate " - until I realised that he probably didn't know what a frigate was.
There is a reason for the word "articulate" to be used inside the English-speaking world - somewhat synonymous with intelligent and educated ..... and remember, with a 200-words vocabulary, it becomes so easy to speak fast.... without even mentioning writing abilities.
But it so good to enjoy that little feeling of superiority towards a colleague doing the job in a foreign language, something that 99% of those ones would be totally unable of ...
Educated people are in any case always easier to understand and to communicate with - somebody eating 50% of his speech will not impress me, either in English or in any other language including mine.