The same principle can work in reverse. If you have an item you love, say a pair of silk pants or a tulle party skirt, and want to get more mileage out of them than the occasional party or office appearance, dress them down. For me, these are a few items that rarely cross out of casual:
thick cable knits
fair isle patterns
Mix and match with messy hair and laid back makeup. Yea! You just expanded the possibilities of your wardrobe.