In fact, no one who replied seemed to hold much in the way of those beliefs, and people generally seemed to believe some subset of what was said in the book.
False beliefs included that Nazis were particularly inventive and influential, or that America was a major source of torture methods, or that there's such a thing as scientific torture.
The true story is that exclusive use of the sort of torture which doesn't leave marks is a relatively modern development (early examples include the Chicago police in the 1920s and the Stalinist show trials), and the evidence strongly suggests that it's the result of monitoring rather than democracy alone. I think it's also the result of a rise in humanitarianism, but this hasn't been covered in the book-- but if people didn't care about governments causing overt damage, monitoring wouldn't matter.
Rejali describes torture as a craft apprenticeship system-- to a very large extent, methods are developed on a basis of plausibility rather than theory, and picked up because they seem reasonable. There's no strong connection between national character and torture methods, but it is possible to track the transmission of methods. I'm reading the chapter about electrical torture-- probably easier to track because it involves relatively recent inventions.