Miss Nellie, have you read Kaya's books? The smudge isn't just any smudge. Hers is made with something she really loves and sometimes gets in trouble over. It doesn't mention the smudge specifically in the books, but with the coloring of it, it just has to be... given her zest for... well, you gotta read the books.

When we went to Chicago, my mom almost had a panic attack when we were leaving the hotel. She had never noticed the smudge before and thought Kaya had gotten something on her dress. We decided to check the other Kayas in the store to see if it was normal. We stood in front of the case in the bookstore, looked at that doll, looked at each other and said, "______ stain!"