The hivecity of Tertium is flooded with heretics that pray to Nurgle and his fetid ways, so it doesn't surprise you to be hit by a revolting smell of... Well, whatever it is, it may have been edible at some point. However, before you can raise your weapon, shoot into the general direction of the smell and be done with who you assume to be a follower of Nurgle, you realize that the smell actually comes from an Ogryn, who is sitting on a (now dented) crate, happily eating... Something. that in combination with the Ogryn's table side manners is probably the reason why you expected to see some cultist of Nurgle stand there.