I'm with Patrice - just pick the side you like best to be the "right" side. Who's to know anyway? lol
I made some removeable throw pillow covers by making the back side out of 2 pieces that instead of being sewn together, just overlapped by about 4 inches in the middle, leaving that part open. Then you can just pop the pillow in & out, and you also wouldn't need to worry too much about the seams, because they will still be on the "inside"!
Good luck!
sue