The Kurdish proverb every ripe and delicious cantaloupe (muskmelon) is eaten by a donkey is one of the most interesting proverbs that I have heard in four languages, including Kurdish, Persian, English and German. I personally use this proverb frequently.
It is obvious that the proverb is a humorous one. It is used in different contexts. Generally it is used when something good is given to an undeserving case. But, in modern usage, many people use it when they want to say that a beautiful, attractive and comely woman marries a ugly, unattractive and grotesque man. This proverb is often used by male sex. The speaker is usually someone who carries a torch for the girl. Sometimes the speaker says this proverb jealously.
A: I can not believe that Sara has married this plain man.
B: It is not strange. Every sweet cantaloupe is eaten by a donkey.
She has probably married money.
Also there is a Persian proverb that resembles the Kurdish one: The ripe grapes are given to jackals.
Is there a proverb that would express the same thing in English?
Unfortunately, I have not been able to find any equivalent in German either.
Best Answer
Rosalind Fergusson, The Facts on File Dictionary of Proverbs (1983) lists two proverbs that seem exactly on point, although I have never heard either one spoken in the wild:
and
Since Ferusson doesn't specify where her proverbs come from, I was a bit suspicious of these two. However, G.L. Apperson, English Proverbs and Proverbial Phrases (1929), reprinted as The Wordsworth Dictionary of Proverbs (1993), cites "Into the mouth of of a bad dog often falls a good bone" in proverb collections from 1639 (Clarke), 1670 (Ray), and 1732 (Fuller); and Wolfgang Mieder, A Dictionary of American Proverbs (1992) notes a recorded occurrence of the same proverb from New York state, although Mieder say that the saying originated in France.
As for the hog-and-pear proverb, Bartlet Whiting, Early American Proverbs and Proverbial Phrases (1977) reports an instance of a similar saying, "The worst pig often gets the best pear," in an English periodical from 1809; other sources claim that the proverb originated in Spain or Italy.
In any event, the two sayings cited above have been recorded in English for at least two centuries and thus may qualify as naturalized English proverbs.
UPDATE (September 2, 2017)
With regard to the Englishness and the proverbiality of these two sayings, Wolfgang Mieder, The Prentice-Hall Encyclopedia of World Proverbs (1986)—which identifies the country or continent of origin for each of the proverbs it lists—has these entries:
although it also has listings for "A good dog never gets a good bone. French," "The pig snatches the best apple. Yiddish," and "The worst pig gets the best acorn. Spanish."
Whether a saying that appears in relatively few published works may nevertheless qualify as a proverb is a question that invites subjective answers. But multiple proverb collections that I consulted include one or both of the sayings given in this answer as English proverbs.