Counter-argument: One of the most successful interrogators of Nazi Germany did not use torture. Quite the opposite really.
Hanns Scharff, "Master Interrogator" of the Luftwaffe.
Scharff was opposed to physically abusing prisoners to obtain information. Learning on the job, Scharff instead relied upon the Luftwaffe's approved list of techniques, which mostly involved making the interrogator seem as if he is his prisoner's greatest advocate while in captivity.
Scharff described various experiences with new POWs, outlining the procedure most of his fellow interrogators were instructed to use. Initially, the POW's fear and sense of disorientation, combined with isolation while not in interrogation, were exploited to gain as much initial biographical information as possible. A prisoner was frequently warned that unless he could produce information beyond name, rank, and serial number, such as the name of his unit and airbase, the Luftwaffe would have no choice but to assume he was a spy and turn him over to the Gestapo for questioning. For Scharff, this technique apparently worked quite well. In addition to initially preying upon his prisoner's fears of the infamous Gestapo, he portrayed himself as their closest ally in their predicament, telling them that while he would like nothing more than to see them safely deposited in a POW camp, his hands were tied unless the prisoner gave him the few details that he requested to help him properly identify the prisoner as a true POW.
After a prisoner's fear had been allayed, Scharff continued to act as a good friend, including sharing jokes, homemade food items, and occasionally alcoholic beverages. Scharff was fluent in English and knowledgeable about British customs and some American ones, which helped him to gain the trust and friendship of many of his prisoners. Some high profile prisoners were treated to outings to German airfields (one POW was even allowed to take a German aircraft for a trial run), tea with German fighter aces, swimming pool excursions, and luncheons, among other things. Prisoners were treated well medically at the nearby Hone Mark Hospital, and some POWs were occasionally allowed to visit their comrades at this hospital for company's sake, as well as the better meals provided there. Scharff was best known for taking his prisoners on strolls through the nearby woods, first having them swear an oath of honor that they would not attempt to escape during their walk. Scharff chose not to use these nature walks as a time to directly ask his prisoners obvious military-related questions, but instead relied on the POWs' desire to speak to anyone outside of isolated captivity about informal, generalized topics. Prisoners often volunteered information the Luftwaffe had instructed Scharff to acquire, frequently without realizing they had done so.
A good detail on the tale and methods used by Hanns Scharff is The Interrogator: The Story of Hanns Joachim Scharff, by Raymond Toliver.
The book How To Break a Terrorist, by Matthew Alexander also describes how the US switched from harsher methods to more persuasive methods after their attempts to squeeze information through torture had failed.
