“The difference is that the lack of tznius is worse in Chabad than any other group which considers itself chareidi, and certainly any group which calls itself chassidish.”
Not true. There are too many Chabad women, even in shlichus, who don’t dress as they should. Someone in the know once characterized their clothing choices as “trendy, tight and tiger-print”. However, there are certain neighborhoods in New York, near a number of leading yeshivos, where the men dress like they just left the Beis Medrash while their wives and daughters dress like they just left a Vogue shoot.