I read this amusing and instructive story about the dress sense of physicists on a Physics Today blog post by Charles Day:
The most extreme example of sartorial insouciance I've witnessed was that of James Heath, a pioneer of molecular computing (and who would probably call himself a chemist, I should point out).
One November, Heath flew from Los Angeles to Boston to give an invited talk at the Materials Research Society meeting. He showed up in the convention center wearing a brightly colored short-sleeved shirt, shorts, and, if I remember correctly, sandals. Not only had he forgotten to dress for Boston's weather, he'd also left his laptop in California.
Did those mental slips matter? Hardly. Using hastily prepared, hand-written viewgraphs, he gave one of the best talks of the meeting. Indeed, it's conceivable that in creating his viewgraphs, Heath was forced to focus more on his message than on its presentation.