And then there was the Spanish 104 student who refused to use accent marks. I reminded her more than once that they were a part of Spanish spelling and that I took off 0.25 points for each accent mark error.
She explained that she simply didn't like them and said I couldn't make her use them.
It's the only time I've met someone with a genuine negative emotional reaction to a diacritic. It wouldn't surprise me if she had some other quirks as well.