"... he converts the offending bit of food from being a 'spot of mustard' to a less digestible 'blot of mustard.'"
That's an example of an interesting edit, found in the manuscript of "A Christmas Carol." The NYT has made the entire manuscript available in high resolution, and there's an invitation to compete to find the other interesting edits. You're supposed to put your contest entries in the comments section over there, and I waded through a lot of reader scribblings without finding any legitimate attempts at finding an interesting edit. There are innumerable musings on the character of Scrooge, and I'm seeing a few people quoting inserted passages they like. I guess actually poring over the manuscript and finding another "blot" for "spot" is just too taxing.