A Smile That Does Not Look Fake
A believable smile is small and uneven. A full grid of identical teeth is the generated look. Start quieter.
A smile that does not look generated is usually smaller than the one you asked for. Closed lips, or a slight part, with the cheeks doing more than the teeth. A full arcade of identical bright teeth, perfectly centered, is the stock expression models reach for when you say "happy, friendly, smiling." For a talking still, a neutral mouth that can move is safer than a frozen grin.
Ask for small
"Slight smile, lips mostly closed, not a toothy grin" beats "big genuine smile." Genuine is not a shape. A small pull at one corner is. You can still look friendly.
Teeth are not a keyboard
If teeth show, they should differ a little in length and brightness. A single white bar is a tell. Count them only if the mouth is open. An open mouth you did not need is an extra failure point.
The eyes have to join
A smile that does not reach the eyes looks pasted on, which is exactly how some stills are built. You do not need crow's feet theater. You need the lower lid to move a little, or the smile is only a mouth.
A worked example
Host about to speak, mouth relaxed, one corner slightly up, eyes in the same expression. A version with a full dental advert is not approved.
Check the still
- The smile is small.
- Teeth are not a single white bar.
- The eyes belong to the same expression.
Where Scro fits
Scro animates the mouth from the still you approve. A frozen grin fights the words. Keep the expression quiet, clone or record the voice, and let captions carry the line for silent viewers.
Approve a quieter smile. Finished samples are on the examples page.
Related: Pores and Skin, Not Airbrush.