We had two problems. One, the developer who wrote the algorithm was the sort of guy who needed to constantly tweak the system. He was a great coder, but he also couldn't produce unless he played a few tricks or hid an easter eggs. So, he kept screwing with the score, making it blink red or suddenly drop and return to normal. We joked that he needed to sell his algorithm to Google. It was fun, but doomed.
The second problem was that marketing started taking the number seriously. They love the numbers, don't they? We were a web shop and at constant war over real estate and advertising. The unwritten law was, anything that marketing took seriously, needed to be screwed with.