Octavius - "Professionalism is/should be judged on your actions and how you come across in person, not your dress sense."
Absoultely.
But it's not, and we have to live in the world as it is, and not as we would wish it to be, or indeed as in this instance, it should be.
It is a simple fact that people judge us on appearence. it's not right, but it is a fact, and we must deal with it accordingly.
Therefore, professional people need to project an image of professionalism, not because it makes them better at their job, but because appearence is about perception, and who has the time to go around saying "I know I look like a tramp, but i am actually a PhD ..." to every single person they encounter.
So although I entirely take your point that no-one should be judged on their appearence, especially if that judgement is negative and erroneous - the fact is that we do make those judgements, and allowances for that simple fact of human nature make life easier all round.