I am a Houstonian and nothing sounds more ignorant to me than a Brooklyn NY accent, so it goes both ways.
I am chuckling to myself :-) When my husband was in the Navy, we had to stay in Brooklyn for a month while waiting to have our car and possessions sent to Newfoundland. We had such a nice landlady but I only understood about 1/3 of what she was saying.... she REALLY had a Brooklyn accent. She probably couldn't understand me either :-)
If a backward redneck began 'speaking' in Brooklyn, Manhattan or anywhere in the Tri-State era, people would surmise it's just some poor schlub with a serious speech impediment. (Which it is.)