These are the questions I ask myself each morning now that I've taken up the summer work uniform of graphic tees paired with dressier skirts (more examples here).
Problem is if I'm sitting across from my boss, I'd rather she not be looking at underdressed me in a graphic tee.
If I'm delivering a presentation & people can see my entire outfit, no problem.
In general, it seems nice to dress for the person who has to look at you. If I'm having lunch with a friend, I wear a prettier top since she'll see mostly just the top half of me.
Do you ever think about this stuff?