Only battings that are needlepunched through scrim have a right side and a wrong side. This is mostly Warm and Natural batting. There is no huge problem with reversing this batting except that placing the wrong side up increases the chance of bearding, especially with machine quilting. If your machine needle is punching through the scrim in the same direction that the manufacturer's needles were punching through the scrim, there is less chance that your needle will punch a little batting through the needle holes.