Weird, the recipe that I'm refining to be my "go to" recipe contains both lard and avocado and I don't get any type of "skin". Of course, I use my bars in the shower, but my daughter likes to take looooong baths, and she hasn't mentioned it either.Oddly the bars that have lard in them did not produce any of the soap scum. Only the bar with Avocado oil produced the soap scum. Basically none of my lard recipes have Avocado in them and none of my Avocado recipes have lard. Kinda weird how that worked out for me.
I shall take a peek at the links you sent me. I am always up for learning something new!