Racist!!! But, I have similar problems with some of the asians around Bradford who've still got very strong twangs of their original accent. Not their fault, and I'm sure their English is far better than my Thai/Indian/Urdu/Chinese/Laotian or whatever. Had some guy asking me for directions to a street he wanted to get to earlier this week. Couldn't tune into his accent at all, I kept saying 'could you say that again' and in the end he just walked off.
Oh, and I have trouble understanding pissed people too.