Weird brown oily substance nasty smelling

This has happened twice, I put my big proven male Black Pastel in with my Butter female and he secrets this real nasty smelling brown oily substance and they paint the entire bin and coat each other with it. The worst part it doesn't come off with dish soap or the fast orange (a grease pumice cleaner). The only thing I have found that will remove it is shampoo and scrubbing. I checked the male and it come out of his hemipenes. If you squeeze like you are trying to pop him, it comes out thick like a blackhead and looks like a long line of dried oils and dirt. He does not do this when with any other female and he has never locked her so for now I just plan on not breeding him to her. I would still like to know if anyone has any insight on this?

Do you have any pics of this?

I've experienced something similar.
One of our snakes would spread this brown stuff throughout his tub and cover himself in it. He would feel super greasy to the touch and like you, I've found only shampoo and water could get it off. I usually use small amounts of dish soap or hand soap, but I found in these instances, only shampoo would work.

But... I'm not sure about the stuff coming out of his hemipenes. In my case, it was just poop. Poop that he had mixed with his water and spread. Poop that smelled especially bad!

I found that sometimes when the males are in with the females, they'll bang around the tub so much that poop is squeezed out.

Wow, romance is not yet dead!

Sorry no pics