I would not be happy with that! I find it hard enough when kids turn up with no socks on as I HATE all things feet related! I would have to tell her that it made me feel ill and was very unhygeinic, especially with little ones crawling/playing on the floor. I would just be upfront, I think, and say "Please don't do that, it's not pleasant"
Ewww, for you, can't believe someone would be so gross/disrespectful