Doug---I agree that if it is listed in SCD or Beckett I pretty much have to have it....and that includes print defects such as the Herrer, Bakep and the 3d Sullivan. Often the Registry ends up listing stuff listed in one or both of those, and even though I am not a graded collector, a listing there adds a lot of competition for a card.
Beyond listed stuff I do collect what I consider unlisted variations and more striking or unique print defects.
I did not mean to label you as a fanatic
. You are one of the most knowledgeable collectors about these darn things I know and I always enjoy and respect your input in this area