Discovered today that one should never build poses into a 3D model and then rescale the model.
I built a head this week, and in preparation for building a body to go with it, rescaled it down to real-world proportions. When I tried the "smile" pose that I'd already created, it translated the control points at the head's original scale.
This was the horrifying result.
But if I ever need to do any "Hellraiser" style effects, at least I now know what to do.