Did a friend's patio turn out wavy even with those spacers? He hired a bricklayer who relied on them heavy, but the rows still looked off. Turns out the guy didn't level the ground right, so the spacers just propped up crooked bricks. After a year, the whole thing is sinking in one corner and mortar is crumbling. Those plastic bits just covered up his rush job, and now my friend is stuck with a costly fix.