This was a comment I wrote to someone in a social network where their avatar was somewhat direct in its presentation.
The first thing people will look at is another person's avatar (profile picture), which often reveals quite a bit about that person. For example, if an avatar only shows a face, then the picture says "here I am, this is me." — People who look for meaningful relationships tend to gravitate towards those profiles that only show a person's face.
On dating sites that are often used for short-term liaisons, photos of people are more direct with what they have to offer, because potential dates then look for something else than a face or a personality. — Yet such photos anywhere in a profile are not effective on sites where meaningful relationships are sought.