Don't Ask: Don't Tell

You cast a spell on the door. Anyone entering the library will say nothing about Emma's state of undress. You will just let her strut around in front of the patrons until you deem it time to let her know what she has been doing.

Emma walks around, blissfully unaware she had removed her skirt and shoes. You think of another change though.

Emma realizes she is barefoot, so she goes back to where she left her shoes. Instead of her sensible flats, there are a pair of gold 6 inch spike heeled shoes. Thanks to you, she thinks these are her normal shoes she wears all of the time. She straps them on, and walks back to the counter to make sure everything is in order. The heels make her butt stick out a little more prominently and add some sway to her walk.