Years ago I stayed at a youth hostel in the Yorkshire Dales in England. The warden turned out to be a Geordie, which means he came from Newcastle-upon-Tyne, in the English north-east. They don't just have an accent there but a full dialect, and this chap was quite unintelligible to most guests. I know that whenever he spoke to me I didn't have a clue what he was saying. Poor chap got very frustrated, as I'm sure he thought he was easy to understand - well, he understood himself - and people were just being perverse. I went back again two or three years later and he wasn't there any more.