If anyone questions me about something I enjoy which they don’t understand then I take the time to explain.
I'm not sure there's any explaining most kinks though, is there? I mean, the vast majority of the population would think it's pretty fucked up to pay random women for sexual services, yet here we are - presumably most people on this forum are fine with that.
A lot of people here are into anal sex, I imagine. Probably quite a few are into fisting too. Anal fisting doesn't seem a million miles away from those two activities, it's just a question of degree of kink. It's a kind of "out there" thing to do, and that's exactly what floats people's boats with a lot of kinks, isn't it? I'm not sure I could explain most of my kinks in any logical manner.
As for getting "covered in shit", there's no more chance of that than there is with anal sex, provided your partner is well-prepared beforehand. Although maybe for some that's part of the appeal too, who am I to judge?
I'm still more curious as to what prompted OP to recant his request so quickly, rather than the nature of the kink itself.