I used to have the attitude of not paying too much attention to how I dressed, because I don't have a high opinion of "superficial" people and consumerist suckers (something like "that's a game I don't want to play, because I think it was invented to make money for the fashion industry").

But when I considered that even I judged people on how they dressed (and on their hair etc.), I accepted that yeah, it's normal that I get judged on that, I should pay attention to it (not that I claim to dress well, I just pay attention to it now).

To put it in game theory terms, if two candidates apply for an interview and you consider that dressing well is costly, then they're playing prisoner's dilemma, hence some of my initial revulsion (my following change of mind could then be framed as "eh, may as well defect anyway", in which case I hope some helpful commenter will offer a better-sounding rationalization).