With regards to FT's first posting...let's be honest - everyone was pretty bad in WWII. But the only good kraut was a dead kraut. No matter how. Charles Upham wouldn't even allow Kraut-made cars on his property after the war.
Yeah but there was a well established code of honour between British and German officer classes that you did not shoot the wounded or prisoners that was taken very seriously by some. Particularly after the Geneva Convention in 1929.
It was the SS and not the regular German army that were responsible for murdering the Americans later in the war after Normandy. I think though that Rommel understood that in this case his own soldiers had broken "the rules" here by feigning death and then firing on Commonwealth troops. He realised that made them fair game for retaliation. Rommel embodied honour on the battlefield and that is why he is so respected by all sides.
It was only in the later stages of the war where things got bad on both sides. Rommel himself described the Africa Campaign as "War without hate" due to there being hardly any atrocities. Still I would imagine in the heat of battle it would be very hard to surrender.
Hitler was keen on shooting prisoners but there are accounts of generals by passively disobeying the order by not passing it on to troops or persuading Hitler to change his mind.
edit: You probably know most of this anyhow.