QH, not everyone has had vast amounts of experience with the whole rodeo scene. Some of us have and know what is commonly worn, others may not know what is appropriate or if there are certain things that are taboo and will get them laughed at.
She has every right to ask this type of question so that she could be better prepared and maybe not feel quite so out of place. If I was going somewhere to an event that I'd never been to before, I would darn sure want to ask the opinions of others who were maybe more experienced and/or knowledgeable.