When you’re searching for a product, like a “black lace cardigan,” you probably want something pretty specific. For this reason, you’ll order product results by relevance, which is actually the default order setting. You would expect for results nearer to the front to be more relevant, then. However, Google’s advertising scheme has skewed results because retailers that pay more for the ad space will show up on the front page. Ultimately, the option to re-order product results becomes meaningless because of this.