I think Joker's point is there a difference between just wearing a french maid outfit to bed, or in the bedroom, and wearing a french maid outfit and actually act like a maid, only to be taken advantage of while you're dusting or whatever.
You can dress up in anything, and then there is acting as something you are not. And in that context, I guess I agree with Joker.
If you get turned on by your wife pretending to have an occupation that she does not, and to act in a way that she normally does not, than that is lusting after something which your wife is not. She's pretending for you.