In games at least, when it's there, it's purple (Dark/Evil takes black). Since that's not a colour that the other 'elements' lend themselves too (except maybe electricity - or evil fire).
Warusame is already dead, being an abyssal and all, as such even items as destructive as Hieikaze's cooking would cease to affect her.
E-Excuse me...I-Isn't that just lovely! Isokaze-chan, let's go hand out the next one!Delicious!Want to be friends?But what flavour is it, then...?What would your name be?Kukii!What flavour...?hmmm...I-It's really that tasty?Isokaze-chan looks super-happy!What does Dark Matter ta-Ah- Hey!Whaaaaaaa!?Aha! Dark Matter flavour!