It's all in the presentation

The profile picture is perhaps the most vital component of a modern dating profile. It's the first point of contact when people view your profile and there is a plethora of information out there on the subject. Okcupid have published numerous studies on this issue, with interesting results.
The research focused on three main topics.

• Facial Attitude. Is the person smiling? Staring straight ahead? Doing that flirty lip-pursing thing?
• Photo Context. Is there alcohol? Is there a pet? Is the photo outdoors? Is it in a bedroom?
• Skin. How much skin is the person showing? How much face? How much breasts? How much ripped abs?

 For men, it was found that a photo that presents the user without a smile is helpful, throwing in a cute animal pic for good measure. Albeit grumpy cat is possibly a stretch. Ab shots do well but only for those who can pull it off.

For women, a Myspace style shot with the camera up at an angle has proven to be most effective , with a smiling or flirty expression preferable. Unfortunately, many guys seemingly have their head firmly in the gutter, and as a result cleavage pics outperform other types, although this is dependanmt on the users physical attractiveness.

More information can be found at: http://blog.okcupid.com/index.php/the-4-big-myths-of-profile-pictures/
http://www.eharmony.com/dating-advice/using-eharmony/the-most-popular-online-dating-profile-photos-revealed/#.Vx4Yz_krLIV