I had another thought that I'd like to add regarding the proposed definition of torture.
That definition, you will recall, is that the sin of torture consists in the disproportionate infliction of pain.
One of the things I mentioned in the course of developing this definition is that inflicting pain in order to satisfy hatred (as opposed to justified anger) is automatically disproportionate. This is because hatred is itself sinful, and so any application of pain in the service of something that is itself sinful is going to automatically be disproportionate.
What we have happening in that case is a separate sin (hatred) that is having the infliction of pain used in its service, causing the infliction of pain to become the sin of torture.
It occurs to me that the same thing may happen in other contexts, and this may play a role in the degredation cases.
For example, it strikes me that sexually degrading someone is automatically sinful on its own. The area of human reproduction is privileged in a way that other areas are not. You can (in principle) execute a criminal for a capital offense, but you cannot (in principle) have him sexually abused before the execution. That's what my moral sense strongly tells me, though I can't think of a Magisterial document that has treated this specific question.
If we take it as a given that sexual degredation is inherently evil then it follows that any application of pain in the service of sexual degradation would be disproportionate and thus create a situation of torture.
Using sexual degredation as a means to another end (like getting info) similarly would not be permitted because you cannot do something that is intrinsically evil as a means to a good end. The end does not justify the means.
So, in addition to satisfying hatred, I think there may be additional sins--like sexual degradation--that will also automatically render any application of pain a form of torture.