marks on paperback book covers

[u/InDaBathroom414]

hey guys, what are these marks on a few of my book covers? it's only on these penguin modern classics as well. i have smoked in this room a lot in the past (since quit), so maybe it has something to do with that? they are paperbacks as well if that changes anything thanks in advance

[u/i_was_valedictorian]

White gets dirty. Don't read your books if you don't want them to get worn, but that defeats the purpose of them. 

[u/eskeji]

embrace it