Because I was 13 years old and had never heard the term before.
I'm sure y'all were well read and worldly at that age and that era.
Your "definition" has nothing at all to do with "Hey Rube!" In fact, if that's what you think when you see "Hey Rube!" then I bet that text in B2 was even more confusing for you.
Bullgrit
Maybe there's a different take on this. Some of us are word people.
I have a built-in spell checker. I don't mispell, I make typoes. (which now I regret saying because I can't recall if the plural of typo ends with 'es' or 's').
I pick up the meaning of words through the context of its usage. In short, I seldom had to look stuff up. And for stuff I couldn't figure out, I either looked it up, or held in in a mental space such that I got the gist of what the author meant and didn't let it block me from continuing. Then later, I'd see a reference which would adjust or refine my definition of the word.
Plus I read comics, which even in the 80's still had a good word to picture ratio pictures and exposed us to lots of science terms.
Conversely, one of my friends with pretty much the exact same exposure and hobbies couldn't spell to save his life. And he was a nerd.
To get back to dog-eared and how my brain figures out the meaning of stuff:
The first time I heard "dog-eared book" it becomes obvious what that means, especially if you've seen anybody fold over the corner of a page. On a deck of cards, by saying "dog eared" you are implying an action of dog earing the cards has happened *because of the past tense on the word eared, implying a verb-like effect). That's harder to visualize, but having played a lot of cards I know what a worn deck looks like. As a writer, I probably would describe a book as dog-eared, but not a deck of cards. Generally, dog-earing happens to a book because somebody keeps referring to specific passages, so they fold a corner down. Though its also possible for that to happen through getting banged around, like a deck of cards.
