Thanks for the post, ajaxfetish - nice read.
Simplifying things a bit, I believe there a few kinds of people among those who will find themselves in a position of "torturers":
1) The brutes. They have a violent nature, they're physically strong, maybe a bit sadistic, you know, maybe they were the bullies in the school yard, and they need some way to vent - "enhanced interrogation techniques" allow them to do that.
2) The "refined" ones - who are just cruel by nature, and who will take pleasure in others' pain, and in inflicting it.
3) The frustrated ones - who, for some psychological reason or other, have a complex of inferiority, and take every opportunity they can find to express that. A victim that is pretty much literally at their mercy is a perfect such opportunity.
4) The "normal" ones - which can't stomach torturing another human being, and, like our lieutenant, will (eventually) resign or refuse to take part in it.

Now, I know that I made the first three categories look absolutely fiendish.
In all truth, all of them can (and are) influenced by propaganda and brainwashing about how the victims are the enemy and they will kill all your children etc. The degree to which they are influenced by this varies, naturally - the ones more indoctrinated will be convinced they are actually doing a good deed, and it's for the benefit of the nation, even if it hurts an individual - you can't make an omelette without breaking a few eggs and all that.

In all truth, I think the usefulness of physical torture is overrated.
Why not use truth serums ? You know what the right questions are, so ask them - nobody is immune to such serums. Even if they have secondary effects - so does torture, and more likely more permanent ones.

Also, why not use the carrot and stick, instead of just the stick.
There's another thing, which may perhaps not always be applicable - most people have a weak spot - their kid, family, pet dog, whatever. Use those against them. It's low, and cheap, but if it works, there is literally no harm done to any of them, and everybody walks away happy: you got the information, and nobody was harmed.

I'm no psychologist, so take all of this with a lump of salt, 'cause it's just my amateurish take on things.

As for the effect on the torturers, which I guess is the point of the article, I believe that people belonging to the first categories won't be affected in any positive way by it. The last type will react like the lieutenant in the article, but the others - if anything, it will make them worse.

There's another aspect to the story - living in a certain environment makes you less sensitive to the aspects of that environment. Most of us wouldn't exactly chew on a sandwich while watching an autopsy being performed one foot away. Same with the torturers - by the virtue of their very job, they become desensitized to the whole aspect - in the end, it becomes another day's work.
It's wrong of us to put them in those positions, and the blame is not on them for adapting - because this is what we, humans, are best at: adapting. If they didn't adapt to being a torturer, they couldn't, in effect, do their job. So they will either get disgusted with it all and quit, or they'll become more or less immune to it and ignore the humane and psychological implications - it's "just a job".

Is this at least roughly in the general direction of the comments you were looking for ? ...