I will never judge someone by what they wear, even in church, teach them? Definately. Judge? Never
A quick story to illustrate my point. One day a girl comes to my church she is dressed in a mini skirt and tube top, a leader goes to her and tells her that she cannot dress that way in the house of God and tells her to come back when she is representable. The girl leaves. What no ones knows until later is that girl was not a christian that she was suffering from depression and had just come out of a bad relationship, she had come to church looking for answers. Two weeks later she commited suicide.
So why not apporach the people who dress like they do and talk to them, become their friends and slowly teach them. Instead of making thread after thread discussing modesty. It would make a better use of your time.