What women are thinking or how women think has always escaped men. So when it comes to what a woman wants in a real man, men are clueless. Fortunately for us, there is science. According to Professor Jessica Tracy of the University of British Columbia:

Women find happy men less sexually attractive than those with expressions that show pride or hint that they have done wrong and know it - Reuters

So guys is you want to get the girl don't smile! Why not?

In a man, a big smile may make him appear too feminine or more desperate for sex. -Reuters

This is why guys need help. We like a lady's smile. 

"Women who smile are absolutely very attractive. That was by far the most attractive expression women showed,"  - Reuters

 To sum it all up, women are looking for tortured souls who don't smile, while men want a lady with a nice smile. So the old saying is true, "Opposites attract".