Well, as an English teacher, I'll chime in here, even though you seem pretty defensive and only want to hear things that are agreeable with your position.
First, when I'm grading 150 essays over the weekend, I'll use the same technique you're complaining about. I balance that with margin notes and notes at the end of the paper with comments on the paper as a whole, but I do not have the time or the inclination to explain every mistake to students I teach. I do teach my students how to proofread and revise, though, in my experience they rarely do either.
Secondly, I want to respond to the sentence in question. I would mark this as well. It wouldn't be because I didn't understand the word, but because I do and I'm questioning your syntax and style. Hubris is a noun and you do use it as such in your sentence. However, that is about as far as I would consider the correctness of its use. Typically, hubris is something one is considered as being guilty of, not in possession of. Therefore, to misplace one's hubris suggests that there is an appropriate placement of hubris, which the definition of the word does not support.
I tend to be cocky, arrogant, and intolerant, no matter how misplaced my hubris may be.
My suggested revision: I tend to be cocky, arrogant and intolerant, no matter how misguided such attitudes might be
Or, if you really want to use hubris: I have been known for my hubris, as I tend to be cocky, arrogant, and intolerant, no matter how misguided this may be.
Personally, I do not see this as something to be proud of, but whatever floats your boat. Good luck, Icarus.