Some people use the term 'orange peel' for the texture of some of those zincolns. I think that fits better than measles. But the issue is any plating blister that pops or area of plating loss due to mechanical striking issues means the coin has a better chance at staring to rot. Zinc rot is bad, and as far as I am concerned, might just make in the far future, some excellent zincolns which survive extremely collectible. Even though billions were minted, the quality at times was so bad.
a very nice XF + 1917 Farthing Woodie cut from a mahogany tree. The bisecting die crack that runs through Georges V ear does travel rim to rim. George V then an 1948 George VI Farthing in Au. that shows lighter grains.
I don' know why, but I really have a soft spot for those Wren Farthings. There's a Proof version on my short list.