I know I've told this story before, but just try to stop me from telling it again: A long time ago at a university far, far away, I met with a first-year student to discuss her essay draft, which, as I recall, consisted of exactly four sentences. I said something like "You've made a good start, but--" and then proceeded to discuss all the things she would have to do in order to fulfill the requirements of the assignment. Then I sent her on her merry way, confident that she would work really hard and produce something that was, at the very least, an essay.
So you can imagine my surprise when, a week later, she turned in her revision, which consisted of those same four sentences--and nothing more.
When I asked why she hadn't revised her draft, she looked at me with a wounded expression and said, "You said it was good." And that's when I realized that she had never even heard all the stuff that came after but because she had stopped listening as soon as she heard good.
Good is a good word except when it's bad. "Good hit!" can refer to very different levels of performance depending on whether it's yelled by a doting parent at a Little League game or by a loyal fan at the World Series, but a player who never advances beyond the Little League meaning of good will never make it to the World Series. And then good is not always pure but often qualified: good try or good start or good, but are all useful as long as the student doesn't stop listening after good.
I use the good, but kind of comment on student work all the time, but I've learned to spend some time in class explaining how students should respond to these comments. The meaning of good depends upon context: a paragraph that is fine for a brief, low-stakes writing assignment might be underdeveloped or inadequate in a final version of a major essay, and a student who sees the phrase good title! and then ignores the revision suggestions I've inserted in the rest of the paper will inevitably be disappointed in the grade.
I also have to remind students that standards rise with time and exposure to new skills, so that writing that is good enough for the first weeks of a first-year class will be woefully inadequate by the 15th week--or, years later, in the senior capstone. An unqualified good on a senior capstone paper is a major accomplishment, while a good, but in first-year writing means it's time to get back to work.
Today I'll hand my first-year students a writing assignment on which the word good will appear in various contexts, and I'll allow them a few moments to bask in the glow of a job well done before I remind them to take a look at the other comments. Good, I'll tell them, is a good place to pause, but don't stop there unless you want your grade to come back and kick you in the but.