My mother is big on dressing a certain way for church - we even had special "church clothes" growing up. The traditional Sunday Best! She used to be horrified at the outfits people wore, particularly the teenagers with slogans, midriff, bikie clothes etc. (The girls in our family weren't allowed to wear nice trousers to church even - long skirts and stockings only!)
Then a priest explained to her that he'd rather people came to church even if they only had rags to wear, than not come at all. She still dresses up for church, but she's not judgmental about what other people wear anymore. Sure, usually it's just their personal preference, but it may also be what they have clean, or what they have. And God probably doesn't care what they're wearing. That always reminds me of that scene in Sister Act actually, where the priest is excited that the street youth came to church!