From Beijing opera
京剧, where painted face colors signal character archetypes:
红脸 (red face) = loyal, brave, heroic (e.g.
关羽 Guan Yu);
白脸 (white face) = cunning, treacherous (e.g.
曹操 Cao Cao). Idiomatically,
唱红脸 /
唱白脸 became the classic "good cop / bad cop" routine.