Thanks for explaining that so well, Lightbrite.
Future Potus: My answer to Reb Shidduch was to a large extent tailor-made to RebShidduch based on what I know about her from other threads.
Therefore, it might not necessarily apply to everyone. BUT at the same time, as a general rule, people do have to consider how they come across and the message they project with their clothing and styles, etc. Often girls are not aware of the image they project and it may not be the image they wish to project.
To some extent, that is what dressing tzniusly is about. What message are you projecting? That can be what makes something untznius. And girls are often unaware.