I have for sometime, I am sure you guys have also, seen descriptions where the seller claims the card is from the most condition sensitive set.

What makes the set so condition sensitive and what set is the King of condition sensitive sets.

Packaging?
Distribution?
Printing Process?
Inks?
Card Stock?

I am sure you know my vote is for T205's but I am not as experienced as many more of you are when it comes to different cards in the Pre-War Era.