It looks to me like a satirical way to expose the truth.
We know there are numerous pre-op males who have no real idea about the consequences of the euphemistic 'bottom surgery'.
I mean, anyone who comprehends ends that a vagina actually cleans itself, constantly, must know what would happen if that feature was absent.
What happens if you stop brushing your teeth?
In terms of the nature of the smell, I too struggled to understand why it would smell like poo, given there was no food anywhere near it.
But it's the smell from the skin used because hormones are released by the act of the ingestion of food. And they make the smell.
(I think that's more or less right. A laypersons interpretation, though).