You forgot, Superman sucks balls!
quoted for truth!
but seriously? if someone didn't know, they could find out SO easy. they could ask the person at the store (book/comic/grocery) they are buying the comic from, they could ask the friend/acquaintance/fuck-buddy they are borrowing it from, or - in the case where they find the comic at the bottom of a garbage can after having ZERO experience with Superman in ANY incarnation EVER in their entire life - they can either look it up on the internet, in a library book or encyclopedia, in the dictionary, OR! OR or or! they can just read the comic and WOW! looks like THIS guy can shoot freakin' lazer beams from his freakin' eyeballs! AND CAN FLY! WOW! and then just... *read* the story. Is all I'm sayin'. People ain't that stick-shit stupid.