Most interesting if seen in the later "slavic subhuman" context what many now (thanks to after war history writing) see as the most driving force behind the Nazi actions which I started to doubt for awhile now.
There are at least two subcategories in German (not Nazi only) attitude towards Slavs:
"good" Slavs having their national agenda fully in line with German chauvinistic objectives and
"bad" Slavs opposing it.
Just some examples:
Poles and Serbs were bad (even today they are) for well known reasons and Slovaks, Croats, Ukrainians were "good" or at least useful.
There was always some DNA-magic behind these stereotypes like "Ukrainian peasants are less spoiled with Jewish blood than Polish Mischlings" but it was a nice good nite story only for Helmut and Helga in SS, HJ and BDM uniforms.
Useful and useless are the keywords.