I don't mind smirk if it's used correctly, though it's one of those words that probably shouldn't appear more than once or twice (at most) in a novel (I disagree with the entire career statement, but taste is highly subjective).
I think some writers will overuse words like "smirk," because we're encouraged to use strong, specific verbs in place of ones that are more vague paired with adverbs, and of course to avoid repetition of words. However, some strong verbs can call too much attention to themselves when they're overused as well (and especially if they're also misused, as smirk often is). IMO once a writer has established that a character is a smirker, the reader will probably imagine them smirking in every situation that warrants it, and everyone will want to slap the expression off that character's face (just as everyone's palm itches to slap smirkers in real life). There are also ways to reinforce this from the pov of an observing character.
God, but Tom's smug, knowing smiles were getting annoying! Sue clenched her fist so she wouldn't slap him.
"Just" has a place too. It's a voice or mood establishing word. Consider the difference between:
I just can't do it.
vs
I can't do it.
The second makes the speaker (or pov narrator) sound more frustrated than the first. But again, if overused, it probably loses its punch and becomes simply repetitive.
I was too, way back when. Even a few years ago, I wouldn't have known the names or definitions for all these grammatical rules, just how to (possibly) apply them. They started to stick after I joined various writers forums and spent a lot of time googling sites like the
Purdue OWL and
Grammar Girl. I often double check to be sure my definitions are correct, even so.
I was taught this stuff but didn't retain it, and for years I was confused about gerunds and participles. I finally decided to re-educate myself on the topic some years back.
