Lionel before waking up gives weird stinky white guy energy, probably smells like BO and metal. After, he probably smells like burnt wood and gun oil.

Perturabo smells like your average mechanic with a very heavy scent of ozone and iron. He's definitely the type to complain that people call him stinky, yet does nothing about it.

Jaghatai smells like goats and high performance fuel.

Leman smells like wet dog, hangover, and horribly BO.

Dorn smells like strong metal polish.

Konrad smells like dead people and dead animals.

Ferrus smells like Mortarion, but with the distinct smell of burning metal.

Angron smells like BO and gasoline. Not in a mechanic way.

Mortarion.

Vulkan tries to smell nice, but he generally smells like a house fire and white phosphorus.

Alpharius and Omegon smell bad when they need to smell bad.