I am a historian, and reading 19th century/18th century handwriting can be the death of me.
This got me thinking, in the 18th/19th centuries, were there people who had awful handwriting that couldn't be deciphered by readers then?
I ask because I can read pretty much any modern english handwriting. Through proctoring tests and grading there is nothing I can't read. I suppose it is because I am used to it.
Back when, were there instances of people not being able to read each others handwriting and giving up or, because they were used to seeing the writing style, could usually decipher writing.
This may not be exactly what you're looking for, but have you encountered "crossed" letters, in which a correspondent wrote part of a letter until the page was filled, and then continued, turning the letter at an angle and writing over the previous text? Presumably done to conserve expensive paper, these were considered difficult to read even at the time. First example of contemporary discussion I stumbled across just now: http://blogs.lib.ku.edu/spencer/tag/crossed-letters/