The stitching on the mattress pad should not show at all. I've pieced batts many times, and some were layered where they joined, but once the quilt is tied or otherwise quilted, no one was the wiser. (Just don't hang my quilts over the windows at the show. lol) What I'm wondering about is lumping. Some old mattress pads that I've seen were all lumpy. So be careful about the quality. But I have used them and had no problems.