Hi EnderD,
I'm having a stressed out brain-dead couple of days, so please forgive in advance...
I totally get what you're saying about the dedicated and inspiring professors, and also that considerate and thoughtful date who also happens to show up in flip-flops and torn jeans. I guess the difference is that of first impression vs. known entity. If I show up in the ER on the verge of a diabetic coma, it's true that I want the most capable doctors and nurses regardless of their appearance. It's also true that I don't have the opportunity to learn of their background or training...and much of my first impression is going to be based on appearances and presentation. I'll have more confidence in those that look "professional" - at least until I have a direct experience of their ability.
Your question about religious clothing is different to me. For me, someone who is presenting themselves in alignment with the traditions of their faith or culture is very different from someone presenting as "counter-culture" ...sorry, can't find a good word to express that thought today. I'm in NY, and encounter Amish folks and ultra-orthodox Jews on a regular basis. Both groups dress and present themselves in ways that aren't "normal" according to the larger culture but are perfectly correct within their own group...and to me.
And...back to that date in the torn jeans...my first impression may be negative, but that doesn't mean it won't change with actual experience of that person.
I know I haven't responded to all of your points...and I'll be back once my brain is re-installed.
