Hi! I've been reading and lurking for months now, but this topic has been on my mind this week too, so you forced me to register and speak up!
We don't have hogs, but we do have sheep and cattle. Two nights ago I mired the tractor in mud at the cattle feeder and by the time I got it dug out, that sour anaerobic poop smell was pretty well embedded in my skin. Why don't I ever think to wear gloves out there??
I have 5 different home-made soap bars on the bathroom sink at the moment :roll: .... so here's what I can tell you. The softer, higher-conditioning, higher superfatted soaps had absolutely no effect on the stink no matter what the scent was. I tried lavender/rosemary/spearmint, chocolate/peppermint and blood orange/spearmint and all I ended up with was sweet minty poop stink. The scrubby bar with coarse sea salt, corn meal and fir/cedar/spruce made a little progress, and the spa bar with 100% coconut oil, and table-grade sea salt mixed 1:1 salt to oil made the most progress in odor removal (I doubt the salt had much to do with it, but it's the only high-cleansing soap I have).
I know that if I had relented and used the Gojo mechanics soap with pumice it probably would have taken care of all the smell, but I'm trying to avoid that kind of thing in the quest for homemade stuff that works instead.
So... I'm kind of thinking that the smell is embedded in oils and because those oils are very close to our own body chemistry, they're hard to remove, thus the conditioning soaps don't touch it. I haven't tried coffee soap or charcoal yet, but if they're known to help with odors, then it's definitely worth a try, but I think I would choose a blend of oils that is very high in the cleansing catagory and with as little superfatting as you can safely get away with. That's because the "cleansing" oils do so by bonding to loose oils on your skin and carrying them away. Make sense?
You've given me the kickstart I needed to delve deeper into it -- I'll try a coffee soap with a super-high cleansing number tonight and report back how well it does.
One other thought (yes, you'll all be glad when I shut up and go back to lurking!) -- if tomatoe juice is supposed to be so good for taking skunk oil and other nasty odors off of dogs, is there any chance that tomatoe juice as the liquid in a soap might lend some of the same advantages?