Q: I’ve been wondering lately about what I call, for lack of a better term, “food words.” Why is someone’s behavior "cheesy?' Or jokes "corny?" Or language "salty"?
A: The adjective "cheesy" has been used in a pejorative way (for something that’s shoddy, tasteless, cheap, and so forth) since the mid-19th century, according to the Random House Historical Dictionary of American Slang.
The dictionary's first citation, from 1863, describes a shoddy orchestra "consisting of the fiddle – a very cheezy flageolet, played by a gentleman with one eye – a big drum, and a triangle."
Oddly, the word has been used in the opposite sense as well (though not much lately). The Oxford English Dictionary has an 1858 citation for "cheesy" meaning showy or stylish. This comes from a sense of the noun “cheese” meaning first rate, as in our modern expression “big cheese.”
We have several other “cheese” words, and their meanings are all over the place. For instance, “cheesed" and "cheesed off" have been used as adjectives for angry since the 1940s.
But today "cheesy" is a negative. This is unfair to cheese, if you ask me. It's one of my favorite foods!
On to "salty." Since the 1840s, we've called experienced sailors "salts" or "old salts," according to the OED. This, as you may have guessed, is a probable reference to the salt water of the sea.
Earthy or racy language has been called "salty" since the 1860s. But I haven't been able to find out whether "salty" language was called that simply because it was spicy and tart or because it was like sailor talk. The references I've been able to check don't say.
The adjective "corny" has a shorter history. It's been a term of derision only since the 1930s, when something that was "corny" or "cornfed" or "on the cob" was rustic, countrified, old-fashioned, or behind the times – and hence trite or hackneyed.
It first was used by jazz musicians, who called a style of playing "corny" if it was outmoded or worn out. Here's the OED's first citation, from 1932: "The ‘bounce’ of the brass section ... has degenerated into a definitely ‘corny’ and staccato style of playing." (Imagine a rube fresh from the cornfields trying to make a splash in the big city and you'll get the idea.)
There's a larger question behind all this: Why do we use so many food words metaphorically? Well, why not? After all, we say that a person who's elegant and discerning has "good taste."