Actually, it was a mistake NOT reserving more human-friendly IP blocks for documentation/example purpose. The three /24 blocks reserved all fail blatantly because nobody remembers them, and they look as unsuspicious as normal blocks.
1.2.3.0/24 would be a much better choice because people would easily remember them and know it's not "real", just like you would not take a phone number 123-4567 on a filled form as "real" (even though it might be).
Next time you make anything, please remember to design for human.