People who smile in a silly way, often because they want to look attractive or friendly.
Simperers might not always be taken seriously because their smiles seem insincere or fake.
Examples:
The simperers at the party were trying to get everyone to like them.
She is one of those simperers who always smiles when she wants something.
The simperers in the movie were trying to be funny, but they just looked silly.
The simperers in the photo booth were making funny faces.
The simperers in the play were so silly, they made everyone laugh.
The simperers in the story were always trying to make friends.