Often in pictures with multiple girls, I find the one that's not smiling to be the sexiest. The others who act silly and smile do not look attractive at all. I'm told I have a pretty smile. But what looks sexier in a picture?
Most Helpful Guy
Not smiling makes the one stand out, the odd one out, not necessarily the sexiest one. Subconsciously, guys see the unsmiling, pouting girl as a conservative, secretive, or "bad" girl, one they'd like to just sleep with. The other smiling ladies are ones guys would actually want to date and be with because they create this persona of being able to let go and have a great time and be honest about what they're feeling.
If a guy should meet these girls in a social situation after seeing such a photo, the one who was not smiling will probably be ignored. If he should meet them each in person, the guy would probably orient the conversation towards a fling while the others would be asked out on a date.
Try a picture with just one girl smiling; the effect is the same, she stands out, but the implications are the same too, she's more comfortable and outgoing than the rest of the group.
Unless it's a solo portrait or you're all going to pout, please, listen to the cameraman, say cheese, and smile.1