I legit thought brown water meant sewage at first, and that they were indeed using it to simulate the smell.  Idk, it just all made sense to me. You're getting up all close and personal with a fat sack of shit, that smells like a sack of shit, in a 400 degree building so he's sweating like a pig, while inhaling noxious fumes from both him and the surrounding environment.. Like damn, that sounds like it would require some SERIOUS training.