That's not much of a question. Do you believe we never do anything consistently that doesn't work? The fact is, we didn't do waterboarding after VN until the Bush administration sought to encourage such law breaking. Again, if you look (in books), and I don't consider myself your personal library, you will find writings from all kinds of sources showing exactly what torture, including waterboarding can and can't do effectively. You will get confessions. Almost no one will ever refuse to confess, regardless of guilt (revisit KSM's long list of confessions). They will tell you anything you want to hear, and you will likely get misinformation. See al Libi.
So, if you're the Bush administration, you get the confessions and intel you want to present. See al Libi. So, for them, it worked. Just not the way they claim it worked. So there was a reason for using it. Also, you might dig a little and find who spilled the beans on the WH concerning torture. There was dissent from within.
So, for me, and try to show me any evidence we actually got anything that was really useful, that we couldn't have gotten another way, and that makes the misinformation an acceptable risk.