It’s a good technique, I’ll grant the man that. Ask somebody’s opinion formally, and they’ll react like you’re forcing them to commit—publicly and irrevocably—to that position. The result? They’ll weasel and double-talk and cover their hoops and spread the blame nine ways to Sunday. Trick them into letting that same opinion slip in a "casual" conversation, and you’ll hear the closest thing to the truth—the closest thing to their real opinion—that you can get out of them without magical mind-probes or torture.