Guy:
OK, there are several ways to get around that formula. One way is to simply leave out the "crime". It is often enough to imply there is some good reason for the spanking, and move right on to the "main event".
All due respect, Guy, I disagree. I think you always have to set up why the spanking occurs. Otherwise you are just writing an action scene. One of the challenges is thinking of new and inventive plots that lead to the inevitable chastisement, be it for sex or punishment. I certainly agree that the overused credit-card-stayed-out-late-shoplifter-smoking-drinking etc plot lines are too overly familiar. That is our challenge as authors--come up with something new and different.
One thing I do is look at other genres. Many times I'll be reading a book like a mystery or historical novel and think "she should have been spanked for that". Or you see a movie and ask, what if...? Case in point, The Graduate. All I can say is, try it and see what you come up with.