I'll agree with you except to say that there should be different standards for those who work in IT. A good 60-80% of people in IT are social misfits or downright anti-social. What constitutes "professional" for them does not involve interacting with other people at all.
They spend 90% of their time TOTALLY away from other people, staring at a computer screen. To an IT person, the standards are reversed: slovenly appearance, messy desks, coffee cups everywhere, are signs of the tortured, introverted genius within. (And I ought to know)...
You could say the same about scientists, researchers, and other types of jobs--they're a bit introverted, but all of them could benefit from a more formal wardrobe. You can't tell me that these people were just naturally sloppy, and the IT profession came along at just the right time, in order to fill their need to be a brilliant slob and receive a paycheck!