May be a bit off topic, but this reminds me of some years ago, my best friend had a female friend who sold her feet. Well not literally, but she was a FOOT prostitute, meaning she catered exclusively to guys with a foot fetish, and apparently that's how she paid her tuition for college. She used one of those pumice stones; she used it regularly as part of her job. I doubt if she's still doing this today, but if they had these socks back then, she likely would have worn them, or at least tried them.
My friend knew about my foot fetish so convinced me to call her. I went to her place and it was fun. I wanted to be tied, she said she had nothing to do it with, but it was winter and luckily I was wearing a scarf, so she used that. She told me she did tickling too, and I could come back for that, but unfortunately I never got around to it.
Later I found out it was all a set up; he told her I was into feet so she got him to get me to call her, because she needed the money. But I didn't mind; I definitely wanted to do it, and when I asked her how much money she wanted she said whatever I wanted to give her. I got my money's worth.
She was cool and I'd see her around my friend's place a lot, so she was more like a friend really, which made it all that much better. But I always found it very amusing; a "foot" prostitute. But what a safe way to do it!