"you can tell who is serious and who is not by noticing who actually stops to think about whether torture is effective. People who don't bother to ask that question are not serious about winning; they're in love with a fantasy of themselves as the person who is tough enough to do all those dirty things that have to be done while other people just wring their hands and whimper."
Yes, but I don't think you give sufficient weight to the fact that human beings, in this era at least (not just Americans, not just Bushites) do that all the time. We live that way. We do what we do not because we have calculated that these actions will produce that outcome but because these actions are consistent with our image of ourselves.
We know, looking at another example, that harm minimisation would work better to reduce drug use than tough enforcement, but we don't want to think of ourselves as people who are soft on drugs (or soft at all, really). That's just about what it means to hold a political opinion.
Any time you hear the words "sending the wrong message" (which is all the time) you're hearing an admission that characterisation is more important than outcomes.