And sometimes tattoos done while in the military can still indicate a lowlife.
e.g. Platner.
Platner's Totenkopf tattoo would have been justified only if he had been an actual member of, say, the Waffen S.S. - and maybe even of an Einsatzgruppe ("mop-up crew" who followed along behind the front lines and "eliminated" the Jews they could find).
Regards,