Generally speaking, Chaos Space Marines don't care about the wellbeing of their mortal serfs/slaves/servants. Therefore, they are less likely to clean the inside of their armor.
Oh boy, you don't have to be a Nurglite to imagine what 10,000 years of superhuman body odor caked on smells like. Casualties among armory serfs are astronomical.
Edited by Indefragable, 06 December 2018 - 12:59 PM.