re: When did the German soldiers of WWII realize they were the 'bad guys'?

From the moment Germany invaded Poland they were killing civilians, Poles & Jews for the most part, and that was done not just by the SS but average German soldiers as well. All of the mass killings in the East, well before the camps were set up, were done by both the SS & German army troops. There are documents that were used in the war crimes trials that proved this. The camps came later; there was mass murder by the SS & the Army well before then. Some of the worst atrocities in Poland early on were committed by Army troops, against the Poles & Jews. They knew.