Seems like , to me anyways, it's pretty easy to end up with imperfections when using a motorized stitching machine. One little stitch slanted just so can screw up the entire line.....so it's not "perfect" but still solid and functional in every other way.
Sometimes they are hard to see, but like someone mentioned earlier, because we know it's there, it glares at us with an ugly frown.
I found out right away that using a machine takes more concentration than hand stitching...quite a challenge for me.
Also, if we want to, we can find "imperfections" in just about everybody's work.