Well, pre-1939 there was scope for argument that the Nazis had done great things for Germany. 6 million unemployed when they came to power, converted to full employment. One of the books I was given by an uncle, who got them as school prizes in the period 1938-40, is the 1940 edition of John Gunther's 'Inside Europe'. This sets out a contemporary view of each European country's government, and is very interesting in that it gives pre-war perspectives on the Nazis, Mussolini, Stalin etc.
However, I cannot fathom how anyone could ignore either Nazi or Bolshevik wrongdoings once they knew about them. And, let's face it, Stalin's purges were well-publicised in the west as they happened - my fath, born in 1928, remembers news items about them.
Ann