The phrase "dumb smile" is grammatically correct and can be used in written English.
It is usually used to describe a smile that is lacking in intelligence or is perceived as silly or foolish. Example: Despite the serious nature of his speech, the politician couldn't help but crack a dumb smile during his press conference.
A man with a dumb smile comes on stage and slices her blouse, exposing her bra.
I have a dumb smile that's permanent!" Pistorius, 24, had both legs amputated below the knee when he was 11 months old because of a congenital condition that meant he was born without fibulae – lower leg bones.
I think it was her dumb smile.
What is it about a chain reaction orchestrated for performing a simple task that has us standing there with our eyes wide and our mouths agate in a dumb smile, craning our necks as we follow the actions?
We kept pumping and after two or three hits I started feeling "tipsy," which basically means my brain started to feel fuzzy while a dumb smile slowly stretched across my face.
But what I also got, and what made me walk out of the theater with a broad, dumb smile on my face, was something that I'd been longing to see realized on screen for ages, and finding it in a Star Wars movie of all places was like the surprise toy inside the chocolate egg.
Before, it had been warm and slightly dumb, the smile of a young lady from a provincial capital, but it had become a mean, hurtful smile, and it was easy to read the resentment, rage, and envy behind it.
I flashed my dumb clown smile and tapped my fingers against my chest.
Martin, in a famous rant from "Planes, Trains, and Automobiles," said, "You can start by wiping that fucking dumb-ass smile off your rosy, fucking cheeks".
I hope, though, that I won't always be split into two sides: the me who is talkative and outgoing and aware and confident, and the me who is constantly apologizing and worried everyone thinks I'm dumb because I smile and nod when I don't want to say "I'm sorry?" again.
Every one of us is implicated in it, too, because no matter what it's offensive: pretty-on-purpose poses are dumb; straight-ahead all-smiles security-pass-style retreats from the ego-strokes of good angles are dumb; photos of somebody else entirely (like, say, Nathaniel Hawthorne, whose picture is my current Facebook profile pic) is dumb.
