The Unworn bonus appears in your closet while playing both Career and Runway Challenges and it gives you a bonus to your Career Challenge score or your Runway Challenge rating if you’re wearing clothes you haven’t previously worn in any challenge. The clothing that you haven’t worn before will have an “Unworn” banner displayed over the clothing thumbnail.  If you tap on any piece of clothing that you have already worn, the “Reset Unworn” button will appear.  By tapping the button and paying the amount of cash displayed on it, you will be able to wear that piece of clothing again and still get the bonus. (edited)