SS was a criminal organisation. Communist party wasn't. Nuremburg.
That people faced inevitable death in case they were captured by nazis. SS "warriors" were held as ordinary POWs.
IMO there is a clear distintion between the
Reichsdeutsche Waffen SS 'classic' Divisions made up of mainly German or Germanic personnel, and the foreign volunteer, the general SS, and SD units.
In general the classic divisions were exemplary in actions and conduct, and were noted on many occasions in giving excellent treatment of Allied POW's especially in Greece '41, and Holland in 1944. The British Para's in Arnhem particulary gave Obergruppenfuhrer Willem Brittich's 9th SSPz Div
Hohenstaufen great credit in the treatment of their wounded and captured.
However this behaviour is tempered by actions such as the massacres at Le Paradis in 1940 by the
Totenkopf, and Malmedy in 1944 by memebers of the
Leibstandarte.
However I think that the Waffen SS in general commited no more atrocities than most combat units in WW2, and is held in low esteem mostly by the actions of the hideous Wachsturmbanne (SS Camp Guards), anti-Partisan units, Einsatzgruppen, SD, and the like who wore the same uniforms, had the same paybooks and papers as regular Waffen SS units, but were not classed as proper Waffen SS.
The Russian front is like 2 kids in remedial classes arguing over marks when it comes to laying the blame in atrocities. The germans themselves had a warcrimes tribunal to deal with the reports of russian warcrimes against it's troops and civilians, the
Wehrmacht Untersuchungsstelle. Certainly no quarter was given on either side and fighting was particulary savage.
As for the communist party not being an illegal entity somehow making its actions somehow more legitimate is a ridiculous statement considering the actions of it's own leadership in the 1930's.
Tronsky
sources:
Hitler's Samurai: The Waffen SS in Action by Bruce Quarrie ,ISBN 0-85059-806-0
The SS: Hitler's Instrument of Terror by Gordon Williamson ,ISBN 0-283-06280-0