Well I believe that's right.
I didn't grow up in NJ, but no one I know says joisey. I certainly never have.
I have never said Joisey either and was born there, lived there for 31 years(besides my post to you previously :).
It is just a funny stereotype that is alive and well in every other area of the US when the Garden State comes up.
Please dismiss my weak attempt at stereotypical humor.