The Russians shot most german prisoners.Of the 90000 germans captured at stalingrad..only 5000 made it back to germany after the war.
Cant blame the russians for their hatred of the nazis...as we all know the nazis comiited dreadful atrocities and killed most of the russian prisoners they caught.Heck they thought russians were sub-human.Very similar to the war in asia between the chinese and japanese.
As for the western allies,they treated the germans quite good.Other than the SS who were shot on sight.
The POW camps in britain/canada/USA were very good,tho.