As for effectiveness, torture apologists will seize at any evidence that torture provided useful intelligence, as proof that torture worked, their definition of "worked" being "there is some slight evidence that the torture of terrorist suspects in our custody produced intelligence which may or may not have saved lives, or generally contributed to our understanding of the Iraqi insurgency/Al Qaeda, etc., etc." By this standard, driving drunk is okay if you manage to get home even one time without killing someone or yourself. Via Andrew Sullivan, Anonymous Liberal demonstrates what torture apologists must actually prove (and so far have not:)
Among other things, you would have to prove that 1) such information could not have been extracted using other means, 2) that the misinformation produced by such methods doesn't overwhelm the accurate information to the point of rending the whole exercise pointless, 3) that the strategic costs of using such techniques (international outrage, increased radicalization of the Muslim world, increased danger to U.S. troops, etc.) don't outweigh the benefits, and 4) the value of the information produced is worth the tradeoff of never being able to use that information (or the fruits thereof) in court and severely jeopardizing any hope of ever convicting that individual in any constitutionally compliant legal proceeding.
All of this would require a serious and reasoned discussion of torture, something that torture apologists in general seem incapable of having, as their defenses of torture generally involve lunatic denialism of torture's severity or factually incorrect assumptions regarding torture's results. That's without even discussing the moral element of torture, an element which is a complete non-starter for torture apologists of course.