I always try to encourage collectors to collect whatever makes them happy. With that being said, I sometimes worry that some collectors may confuse the Universal Coolness Index with established Fancy serial numbers. You need to look no further than the first note posted on this thread - JK00707077A. This is an interesting serial number, but it's not Fancy. It's not a Solid, or Repeater, or Radar, or Ladder, or High, or Low. The only auction venue that mentions the Coolness Index is eBay, and that's because sellers write their own auction descriptions and take their own photos. You will never hear the Coolness Index mentioned on Heritage
or Stacks or Lyn Knight or any other auction venue where professionals write the auction description. Once again, collect whatever makes you happy, but be aware that a high Coolness Index number does not always translate as valuable or desirable by other collectors.