Richard Stallman deliberately tells you his website/etc is powered by free software. You can infer from the http headers of my homepage that it is powered by free software. Stallman is making a statement, my host (NYU) is just not bothering to obfuscate headers.
Similarly, a person who wears comfortable, easy clothes is just revealing information. A person who actively selected their clothes based on the message they send is making a statement.
What I meant was statement in the sense of fashion[1], which is the connotation of your clothes, 'reavealing information' as you put it. But if you are deliberately buying geeky t-shirt or 'easy' clothes, you are still making a conscious statement, for example "I'm a geek" and "I prefer comfort over fit". In the event that the selection of your clothes is not deliberate, there's still the connotation of them. For example, with 'easy' clothes some may look at you as a slob, while others sees you as laid back.
While you can be outside of the 'fashion system', your clothes still have meaning, to you and to others. If you want to read a proper simile regarding fashion, i.e. not with http headers, I can (almost) recommend the works of Roland Barthes [2].
[1] http://encarta.msn.com/dictionary_561533193/fashion_statemen... [2] http://books.google.com/books?q=roland+barthes+fashion