http://wws.princeton.edu/news-and-events/news/item/split-second-clothes-make-man-more-competent-eyes-others

Pretty obvious I guess but:-

Faces were judged as significantly more competent when the clothing was perceived as “richer.” This judgment was made almost instantaneously and also when more time was provided. When warned that clothing had nothing to do with competence, or explicitly asked to ignore what the person in the photo was wearing, the biased competency judgments persisted.

Clothes are an important part of increasing one's SMV, I am personally reaping the benefits of this without even lifting yet.