I have worn jeans to a show before... I don't think the argument is so much the fact that people are wearing jeans, it's the fact that they don't look presentable. I've been known to wear a nice pair of jeans, heels and a nice top to a show.... and I've also been known to be dressed to the nines for a show.
I've been appalled at seeing how some people come dressed to shows.. One kid (who had rushed tickets) was denied entrance at Chicago at the Ambassador because of the way he was dressed.... well that and the fact that one of the ushers heard him talking and saying that he hadn't showered in 2 days because he didn't have a hotel while he was here...
I remember going to see Rent when it first opened. I hadn't been to a show in a few years before that.... I showed up in a dress, and heels (nothing outlandish, it was a simple slip dress) as I was taught that you get dressed up for the theatre, and I was shocked to see how everyone else was dressed! I actually turned to my aunt (who had gone with me) and said "I feel over dressed... when did it become okay to go to a broadway show looking like you just rolled out of bed?"
Oy.
"You're every gay man's wet dream!" ~ MA
If in Heaven you don't excel, you can always party down in hell...