My handwriting was, and is, messy and hard to read. When I was between 11 and 13 years old I had a history teacher who believed students’ work should be neat and tidy. The result of this was that I was constantly marked down in history due to my handwriting.
While this history teacher wasn’t the only one to comment on my handwriting (and indeed, the school put me into a special ‘handwriting’ class at lunchtimes to try to improve my writing) he was the only one (that I remember) who continually marked me down on the basis of my writing. I definitely felt at the time that the quality of the content of my work didn’t matter to him as much as a the quality of the presentation - and I felt this was stupid.
In the UK at the time generally one dropped down to studying 9 subjects at the age of 14 and although I loved history timetabling issues with other subjects I wanted to study meant I ended up dropping history. I wouldn’t attribute this directly to the teacher’s attitude to my work, but I think it must have contributed to me prioritising other subjects when I was faced with dropping some of my classes.
Could anything have been done to fix this after the fact? In general terms there was a fix to avoid my messy handwriting being a factor in my work and in comments on my work - I was lucky enough to get a home computer around this time (a BBC Model B with 32K of RAM! This was 1986 so it was not so common to have a computer at home) and, with agreement from the school, I was able to submit at least some of my work typed on the BBC B and printed out. These days I very rarely write anything beyond greetings cards by hand :)