If I had to eliminate the variations and just pool all grades together, this is what I get:
My A grades: You are the students who do the assignment. You do it on time; you write a little bit more than the minimum page length. You come to all classes. You aren't brilliant, but you do all the work and you do it satisfactorily. Sometimes you make me think. Usually, you just stay out of my way. I don't have to write extensive corrections on your homework. You make my life slightly easier. And so I give you an A.
High Bs: You come to class most of the time. I have to try harder to get you to keep an eye on basic things, like grammar and content, but it isn't ridiculous. You write exactly 2 sentences more than the minimum page length just to cover yourself. You do the work, you send me the occasional whine, but we don't clash so I give you a high-ish B.
Low Bs: You are on the verge of not caring at all. Some of you really struggle with the reading because you come from a personal place where learning wasn't necessarily a priority. I totally get that you had kids, or your parents didn't read to you, or you spend a lot of your spare time working and dealing with real life. It makes my job harder, but you're getting by. So I give you a lower B.
Cs: You don't read the assignment. Some of you are smart and half-ass it because you can. Others are trying desperately to understand what instructions mean, to no avail. Your margins tend to be at 2 inches, or you add extra spaces between your paragraphs, or the font is at 13 pts. Attendance is not a priority. Some of you C students come to my office hours and try to convince me to give you 2 extra points here even though you are still 30 points away from an A. This very act underscores why you are earning a C: trying for a 1% extra credit grade does nothing compared to writing a full-length, course-material-focused paper in the first place, which would be worth so much more. You take up a ridiculous amount of my time and I probably spend twice as long grading your work than I do the B students. And so I give you a C.
Ds: Most of you sleep through the first half of the semester. You submit papers that are sort of on topic, but clearly not written in response to my actual question. An assignment on the beliefs of Christianity might be answered with a devout personal expression of your relationship to Jesus. Alternatively, you answer the question, but you never pass the halfway point in the required paper length. Late work is common. So is the end-of-term request to redo work, make up "lost" submissions, and perform extra credit or makeup exams. You are the students most likely to challenge my grade or ask for post-semester "help" as though that would change anything. I hate negotiating with you, but still I give you a D.
Fs: You either never show up or you plagiarize. You usually never contact me after I have failed you, because you did not speak to me prior to submitting carefully copied work and are too embarrassed for our first interaction to be lies about cheating. You require less work than my A students, but I get paid exactly the same. For that I rather like you. But still, I give you an F.
Note, if you will, that none of these students are "promising" or "rewarding" or "the lifeline for my teaching career. (#Katiefromkalamazoo) But hey: paycheck!