When I was studying computer science in college, I had one extremely tough professor. His name was Dr. Maxey and he taught the more complicated courses like data structures and computer architecture. He was a wonderful teacher with a talent for articulating difficult concepts, but also an extremely tough grader. Not only would he look over your code to make sure that it worked, he would take off points for stylistic issues.
If you were missing appropriate comments, or even if you misspelled a word or two in your comments, he would deduct points. If your code was “messy” (by his standards), he would deduct points. The message was clear: the quality of your code is not just in its execution but also in its appearance. That was my first experience with coding style.