Dressing well is not always about power dressing, its not necessarily about trying to impress.

It can be about complimenting the people you are meeting with. It can say, "I took the trouble to try to make myself look presentable/attractive in your eyes because I value your opinion".

I think we say as much about how we feel about others when we dress in a particular way as we do about our own self-esteem.

When we go on a first date, for example, the way we dress gives clues about us. Shoes clean and heels not worn down? Clothes fresh and well fitting? Hair brushed or artfully mussed? Nail varnish not chipped? It all adds up saying to our date "I care enough about our meeting to make the effort".

Dressing well can be just an extension of good manners, of making someone else feel appreciated.

I'm not saying it also cannot be "Look at how expensive my wardrobe is compared to yours".

Depends on the person I suppose.