I can't imagine what a person wears has anything to do with going to the theater Well, not anymore than what it says about you as a person in general.
As many have said, I'm often out for the day while in the city so I'm going for comfort and practicality.
As long as someone else's attire doesn't cause a distraction to my enjoyment of the show, I don't pass judgement.
Again to show the change in times but more recently: I bring my HS students to NY for a theater weekend every year. As recently as 10 years ago, it use to be that during the rest stop for dinner there would be quite a transformation: the girls would go into the bathrooms in their jeans and come out dressed to the nines for the evening show. Of course, they still had to endure another few hours on a bus before arriving to the theatre. Now? No change, whatsoever.
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.