I'm not sure if this applies to other Pillage skills, but I can use Steal Helmet on a character with no helmet.
EDIT: The Fitting Room doesn't seem to function. When selected, it simply says "Who wants to try it on?" then closes out of the shop.
EDIT: The Fitting Room doesn't seem to function. When selected, it simply says "Who wants to try it on?" then closes out of the shop.