Now that's a whole other discussion. Some would argue that the 'standards' (lack thereof?) are too relaxed...
Chabad tznius standards are very peer-pressure oriented. They're very different in every place.
I know here in CLE standards are more strict than Chabad standards in say LA or CH. As some 15-20 new chabad couples have joined the CLE Chabad community in the past couple years in I think it surprised many local folks with how lax standards of some can be...
Regardless, Chabad girls do know how to dress well, even the ones that do follow tznius halachos