Wanda generally believes Stanley to be a fool, but does believe that he has an important fate. She was subservient and loyal to him - In fact, Wanda was probably the creature Stanley trusted and respected most in the whole Erfworld - but secretly continued to play events to bring her closer to the Pliers.
She has used sex to manipulate Stanley. This might explain her revealing outfits.
Since Wanda's attunement to the Arkenpliers she seems to be happy to go along with Stanley's orders as long as she can play with her Pliers and her personal army. Stanley feels somewhat insecure about this new balance of power.