It's one of those things that isn't high on the list of things to pay attention to - dressing for an interview. Especially in academia/research, and especially in the physics profession, dressing appropriately isn't something that we pay that much emphasis on. I mean, during the summer months, I come to work in shorts, t-shirt, and sneakers. So one can already tell that I am not that "fashion conscious" (just don't anyone dare call Stacy and Clinton from "What Not To Wear"!).
Still, when one goes for a job interview, even for a job in physics/sciences, what would be appropriate to wear? Well, the Science career section this week has good tips for what to wear and what not to wear. It covers a wide enough situation, from formal to less formal, that one can buy a wardrobe to suit almost all the possible needs. And this covers for both men and women.
From the point of view of the interviewer, I would like your ability and your knowledge to stand out. This means that your outfit and how you are presented should NOT be a distraction. If you walk out of the interview and a day later, I don't remember what you wore, but I do remember exactly what you said, then you have done a good job in dressing yourself. We care more about your knowledge rather than your appearance, but your appearance can be a hindrance to our focus in deciding on what you know.
Luckily, I don't think I've ever come across an interviewee who hasn't dressed appropriately. And certainly I haven't come across anything similar to the person mentioned at the beginning of this article (it just shows lack of respect more than anything else, and that would have turned me off as an interviewer).