You are right You stink Although fungus is not a proper answer There are fungii that smell like roses on a summer morning
All I know is they smell bad, I mean they aren't the most hygienic bunch. Oh and commenting on an orks odour is probably more of a compliment.
In newer editions, however, adult Orks are constantly giving off fungus-like spores which lie in the ground of worlds they invade or settle, often for years, waiting to develop into Orks or Gretchin. Thus a world invaded by Orks will be troubled by them for hundreds of years to come, even if the original assault is beaten off. Might be mold, they are fungus that smell like crap, as much as "SOME" might smell like roses they do not. Maybe the answer your looking for has something to do with diarrhea?