I took an interest in clothing when I realized clothing is another way to communicate. The programmer who doesn't care about clothing is not far removed from the programmer who doesn't care about small talk or politeness because it "doesn't mean anything".

In particular, one important thing clothing does is guide the eye of the viewer. Why are graphic tees unprofessional? Because they are distracting to the viewer. Why are suits professional? Because the details--lapels, tie, collar, padded shoulders--naturally bring the eye to the wearer's head, making him the center of attention.

Presentation is important, and affects the perceived content of that which is being presented. It puzzles me that many good programmers understand this about everything except clothing. If one were making a web site, the importance of color coordination would be obvious. Why do programmers so often neglect it when dressing one's very person?