does a picture make that much of a difference?

All dating sites say the same thing , add a photo and you will be more "markatable" but is this actually true?

When you are staring at a blank picture slot of a potential encounter all is possible this person could have every thing you are looking for, every tiny detail that will turn you on and non of the things that turn you off. The moment that person adds his or her picture , its out there for the world to review and you can see that just by looks that they have something that you do not like and instantly the oputunity is lost for the person who added the picture where before people where willing to take the risk , but no longer.

i think the driving force of this is the same as the driving force of humanity , hope. It is so crucial to our survival that most people dont even register it.
Why do we get of bed in the morning , cause we hope it will be better than yesterday.
Why do we continue to search for relationships if hurt badly in the previous one? hope that it will be better

and why are we more willing to extend out a hand to a faceless person? the hope that they are everything we desire...