@clacke
Very true. Unfortunately many of those books are unpublishable or just dull.

@ghostdancer In 700 years, the meaning of words shifts and often changes totally, or the words fall out of use. So no, it is not easy even for a native speaker.

For example "Gay" used to simply mean cheerful until around 1960. "Nice" used to mean evil. "Sophisticate" used to mean a simpleton or ignorant person.
Slang is something else.
When I have been in France, I have often stumbled over words that aren't in any French dictionary of phrasebook.