The current documentary Essex wives was a nasty piece of work that made my blood boil. Essex women are like any others.
Apparently theres a historical basis in the stereotype I've been told. In the past women from Essex were always viewed as rather independant women who supported families and ruled the roost. From this there grew jokes about their nagging etc. and out of this jokes about their sexual laxity (if you want to get psychologial about this, the easiest way to attack a strong woman is to imply that she has the morals of an alley cat.)
I live in Essex, although not Essex born and I get the jibe wherever I go. I don't take it personally because very few people actaully mean anything by it, its just a conversation opener.
Edit-in fact thinking it over, moving here from London as a kid I remember how reserved and quiet people were, men and women, and it's still the case. Yoi can stand in a bus queue here and nobody will talk, go to big soul-less, uncaring London and you can strike up a conversation in 30 seconds.......
*strolls off holding braces and singing 'mabbe it's becorse I'm a Londoner'*