I have noticed that practically all the women at SSPX chapels wear skirts but a higher percentage of women at FSSP chapels wear slacks.
Why this difference?
I have never seen a single regular parishioners at my FSSP parish wear anything but a skirt or dress.
There are probably well over 500 parishioners.
I have definately never seen "tight blue jeans" or "short shorts" on anyone there.
Occasionally, a denizen of the surrounding ghetto wanders in dressed immodestly, and definately on large Holy Days there are a lot of newcomers that are dressed immodestly.
I've never seen evidence of any of the priests "tip-toeing" around modesty either. Quite the contrary actually. They don't have a dress code announced on their voicemail (which is just tasteless really), but they do put out an announcement in the bulletin during the summer, etc.