Would a Mongermonger be the person who arbitrates whether a given trade or calling can be mongered?
That reminded me of the Little Britain Tom Baker voiceover, when he said something like:
"In Britain, if you want to buy a pet, you go to a pet shop.
If you want to buy a pet shop, you go to a pet shop shop.
And if you want to buy a pet shop shop.... you're just being silly now!"