I've noticed that the majority of pictures in showcases/ads that show the face of the provider do not feature a smile.
Obviously, there are exceptions, but for the most part, there's a "serious" look to most of them. Maybe this is meant to be sultry, sexy, but to me, it just comes across as dour in many cases.
With very few exceptions, I think any girl with a happy smile is prettier/sexier than that girl without.
Again, obviously, there are types of photos that do not lend themselves to a smile (BDSM, for example), but most, I think, could be improved with at least the corners of the mouth upturned, if not a full-on grin.
Maybe part of it is the self-shot photos. I would find it strange to smile at myself. (As opposed to laughing at myself, which comes relatively easily.) But it seems like a lot of the professional photo sets feature grim-looking girls.
Duck lips, on the other hand, well . . . Let's leave that for another thread.
I personally love it when a man smiles and think that people in general look better with a smile (since we're speaking about smiles and not necessarily the teeth...). It takes more muscles to actually frown. Even if you don't have that "twinkle in your eye" when you smile, a smile is always more sexy and inviting
