The intent of the two guidelines is to prevent the negative effects of log deletion without eliminating challenge caches.
Mystery or Puzzle Caches
Challenge caches incorporate special logging requirements and are listed as Mystery/Puzzle caches. Typically they require the seeker to have previously met a reasonable geocaching-related qualification (Waymarking and Wherigo qualify too, of course) such as first finding a cache in every county in your state. If you are thinking of creating such a cache, please include a note to the reviewer demonstrating either that you have met the challenge yourself, or that a substantial number of other geocachers would be able to do so.
The farmer gave permission to place the cache in the field, but the bull charges.