Wow, this one IS tough. I don't know. I was in the research science field for my entire adult life. Some of the most disheveled, poorly dressed people I have ever met have been doctors. I mean really prestigious researchers, including two Nobel Laureates. But I knew of them BEFORE meeting them, so their appearance didn't bother me. Actually, most professionals that I have gone to that are disheveled or "improperly" dressed, I have known of their reputation ahead of time......
Alternatively, we once hired an impeccably dressed owner of a construction company and the guy turned out to be a crook.
So, I think that in the end, you have to feel comfortable with any professional you are thinking of hiring. I also think that when you take everything into account, you should listen to your gut. If you felt uncomfortable, that is not a good sign. You strike me as a very genuine and tolerant person....so I tend to think that your instincts may have some validity. I tend to think this is not just about how she "looked". Maybe you felt is was a sign of disrespect for you, the client.
PS _ I don't believe in "authority" figures, except police, etc. They are just people with different jobs from us. In fact, there job is to service YOU, that is not authoritative.