While I don't have the problem of a messy knitting bag (yet!) since I still haven't figured out where I can carry these things, I do have splatters and flour dust ALL OVER my cookbooks.
Tangental: It's like the Velveteen Rabbit (a bedtime story): being used, and well-loved, is much better than being pristine. In the story, the toys that were loved by children in the story turn into real animals when the toys get thrown out, and the main story is about a very well-loved little rabbit. It was one of my favorites as a child.
Return to conversation: I have hand-copied the Palindrome (k2, p2 for 5 rows, then the cable row, it's very simple) onto a 3x5 that I stuck in my wallet. I suppose this wouldn't work with a sweater or something, but you could hand-copy, say, the arm that you're working on at the time.