When I was in middle school, I had one of those books put out under the American Girl name that illustrated basic etiquette for young women. Although I'm sure it was useful, featuring detailed information about writing a thank you note or not asking inappropriate questions, the one message that really stuck with me was in the introduction, which described why the niceties of common etiquette were important. The book argued that good manners are not formalities, but ways of showing people that one loves or admires respect. Good manners make people feel comfortable.
This extends to clothing, in a way that is especially relevant for women. Wearing, for example, skirts of appropriate length to the office and shirts that do not bare excessive cleavage to class is an important way to show respect to other people. One easy way to think about dressing appropriately for any occasion is to consider who will be there, and how they will feel about your clothing. This doesn't mean dressing for other people. This doesn't mean personal expression via clothing isn't valid, it means that it's not fair to show off a new push up bra in early classes, whether the professor and/or classmates are male or female. If the people around you are happy and comfortable, you will be happy and comfortable too, as well as confident.
To carry this toward the vicious and delicious world of reality television, we might consider the first episode Stylista in which one of the young women earned the nickname "Boobs" for her excessive display of cleavage. It's tempting to think that she was picked on because of jealousy, or because the drama lent itself to reality television, and that's probably true. On the other hand, I do not think it would ridiculous to say that the contestants, and the management, fixated on this character's breasts because the blatant display made them a little uncomfortable. And that's the thing with inappropriate dressing, whether it's an obviously unclean outfit or a pair of jeans that show too much: they pull attention away from the task at hand. Wearing inappropriate clothing, like so many other breaches of etiquette, is just another way of claiming that you are more important than the people around you.
general housewifery is participating in National Blog Post Month (NaBloPoMo).