Well.. it was my understanding that the generally accepted reading/writing convention in the west, particularly with English languages, was that you read left to right and top down. This is also how you write.
When writing in a smiley face, the source generally being a real face, you read the face from left to right and top down. Since it is symmetrical, left to right becomes irrelevant and top down becomes the rule of transcription. Top is the eyes, down is the mouth.
Then when transcribing to print you write left to right, top down, eyes were first mouth was second.
Eyes :
Mouth )
Complete
Unless, of course, your subject is Jake Tucker. http://static.episode39.it/character/888.jpg
Reverse smilies just weird me out.