I grew up in Dallas, Tx in the 70s and 80s and I will tell you something we all knew back then, but seem to have forgotten now. You dress one level better than your audience, IF you want to have an impact. My momma told me, “Paul, it is hard enough to succeed with brain power and politics, why make it harder by dressing like a slob.” That didn’t hurt my feelings of course, I’ve always been a clothes horse and always will be. I do not mean you wear a tux to a hackathon, that is the opposite of understanding style, though if I thought it would help me accomplish whatever it is I needed to accomplish, why not, tuxes are fun!  My friend, John Zachman, has a black bow tie. I am the one that gave it to him. We aren’t friends because I like bow ties, but it didn’t hurt much either.
We are geeks, dorks, nerds. We are mathematicians, physicists, and scientists dammit! Clothes are unimportant! It is only ideas that matter! And yet… The way we look impacts how our message is received, our credibility with an audience, and the degree in which someone will invest their own time in us and our vision. Almost 80% of communication is non-verbal. It is posture, clothing, styling, inflection, tone, and facial expression. Of course I understand that your idea is the best idea that has ever been had by anyone. That you have ALL the ideas and they are terrific! And, of course, you won’t be fired because you decided to wear those dirty jeans and a the van halen t-shirt. But I wont be giving you the keys to the executive suite either. Not unless you have some serious personal mojo that makes those dirty jeans somehow really cool. Or you are Richard Feynman. Either of those are ok. But the vast majority of us are not that.
Think of it this way, no matter how great your class description is, a badly defined interface will always cause problems. Dorky enough for you? Next time you go to a meeting, try a crisp white button up shirt with french cuffs (and as geeky a pair of cuff links as you can find-we are NOT giving up our roots here!) and a spectacular vest (please start with greys, browns, blacks and dark blues at first, as vests can go wrong very quickly).
Ok all joking aside, the business world takes a few technologists seriously and if you are one of them, then please feel free to wear a mock turtle neck or a grunge t-shirt or whatever. But if you are already one of them, you know the value of style in the workplace and with stakeholders. For the rest of us, the impact of a nice outfit can be almost confusing. For example, early in my career I had a hard time interacting with coworkers. I found, that if I wore a suit to work (this was in Austin TX), people would come talk to me instead of me overcoming my fear of speaking with them. Dress has gotten me into more meetings, more business opportunities than anything other than my mind (terrifically brilliant mind, other people wish they had my terrific mind :-)). Don’t believe me? Try it for one month.
If all else fails, think of a suit (and please get a well dressed friend to help you pick a decent set of clothes, not your great grandpas wool 3 piece), as a trojan horse. They will get you in the castle, then we will see if your technical ideas and business acumen can keep you there.
For my lady nerds, this means you too! I mean really, ideas may be able to change the world but you still have to be able to influence people to get the work done (at least until the singularity).