Caliban bearrs the brunt

Trin. Monster, I do smell all horse-pisse, at which
My nose is in great indignation

Ste. So is mine. Do you heare Monster: If I should
Take a displeasure against you: Looke you

The Tempest, Act 4, Scene 1


Although Stephano is angry with Caliban, it's not Caliban that smells of horse-piss, it's actually Trinculo and Stephano who pong. Ariell had caused them to dance in a stinking bog:

"at last I left them
I' the filthy-mantled pool beyond your cell,
There dancing up to the chins, that the foul lake
O'erstunk their feet".

Question: Would a boggy lake smell of horse urine? If not, where is the horse?

cheers

No thoughts on such a base subject? I be pissed off, as Caliban might have said.