When I was a student, I often had a cold and was absent from school.
A few times I couldn't take a test of German composition. In those cases we had to make up for it by translating Tensei-jingo into German, and we had to hand in our translation with the original text in Japanese. This compensation was much harder than taking a test, but I rather liked it because the professor corrected the translation very carefully.
Once in such a case I handed in my work. At the next time I met the professor, he told me to write the text by myself. At first I couldn't understand what he said, and as soon as I found it out, I was very shocked, depressed, angry, and felt betrayed. He doubted that somebody helped me with Japanese writing, only because my writing resembled somebody's.
If he had understood what I am, it could have never happened. After that I lost my trust in him, and I quit attending his lecture.
Whenever I remember this affair, I feel deeply hurt even now. Both in teaching and learning it is very important to be able to believe each other, I think.