"mirror checking" is correct and usable in written English.
You can use it when referring to a self-reflection process in which one examines their own actions and beliefs. For example, "I've been doing a lot of mirror checking lately to get a better understanding of myself."
While she was waiting, she was looking in the mirror, checking herself out, like this... ' Lily pulls a ridiculous face.
Before she stepped outside her house, she recalled, she would scrutinize herself in a mirror, checking to see whether her blouse was too tight.
But just the way I used to spend a lot of time looking at my body naked in the mirror, checking to make sure things were O.K., I now spend a lot of time looking at my brain and wondering if it's up to snuff.
Perhaps I was able to accept it from Mrs. Lynch as I had from no other because there was no self-love in what she did, nothing showed me she had one eye on some mirror checking her posture as the comforter of a grief-stricken child.
And speaking of mirrors, if we had a dollar for every minute that girls/women and gay men spend in front of the mirror, checking themselves out to ensure we look good, we could pay off the United States National Debt! (Just don't tell the politicians that, they'd never give us a cut of the funds for the discovery).
Don't spent hours looking in the mirror, checking yourself out, or asking your friends if your new kicks are ridiculous.
In another room, a woman checks out every inch of her naked body with a hand mirror in a re-creation of Joan Jonas's 1970s work "Mirror Check".
If the dresser has a mirror, check for cracks, chips or spotting.
Do a quick mirror check then grab your stuff and go.
Using a hand mirror, check your buttocks, genitals, lower back, upper back, and the back of your neck.
If you plan on hanging the bedazzled mirror, check the hanging apparatus on the back of it.
