I see people greeting one another with face kisses – mostly in the western part of the world. I have friends who did that to me too; It was kind of awkward at first but I gradually got to like the practice and the meaning behind.
I find it interesting that the number of times you go left and right depends on where you are from and familiarity. Sometimes, the frequency varies amongst people from the same area.
I always get confused. But I like the confusion since it amuses rather than frustrate. Also, there is an odd feeling in my chest when that happens, particularly with good friends – like finding out flowers have started to blossom on your favorite plant.
Not sure if it would work in a cosmopolitan city that is moderately conservative, but I wish we had a practice like that here.