[Astromancer]

A Quirk level version of Unusual Biochemistry is what Odd Smell works out as. The effects are somewhat random but often annoying. Animals either fear you as a strange beast or totally ignore you. You either bug people in some way they can't define, or you really turn them on, or they can't care about you one way or the other period.

The fact that these effects can sometimes be useful, sometimes a pain, but mainly even out in annoying ways, makes this a quirk.

For a perk version try No Smell. It's a very limited form of invisibility, but sometimes useful. Example: Bloodhounds can't track you.