True @Arimara - I wouldn't make or use use dairy butter in soap if you paid me!Dairy butter soap makes an incredibly stinky soap with no way of remedy for it. It truly becomes a wasted resource better left to some toasted or fresh baked bread at the least. Would I judge someone for using it? Yes, I would if I had to allow that person in my home or if, after the numerous complaints/warnings on here were ignored, they complain about their dairy butter soap.
@kdm have you considered making @Zany's no slime castile? That would be an easy one. I'd still go for 10% CO in it though, but that's just me.