I think it's simply rude to gossip about other people riding, cloth, etc. (as long as it's not an abuse or dangerous, and even then instead of gossiping and ranting on Internet I'd just say so right to the person). Feeling "superior" is never a good thing...
I ride in some cr*p of old pants in my ring. I don't care what other people think about me not dressed "appropriately". It's comfortable for me and that's all that matters. I'm sure I do mistakes when I ride too, but that's what my trainer is for: to critique and teach.
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."