The problem with onions, almost all agree, is that they smell. Onion breath has been bedeviling the socially sensitive since the first hunter-gatherer ate the first wild onion bulb. Once you’ve eaten an onion, everybody knows it, which is why Don Quixote cautioned Sancho Panza to “Eat not garlic nor onions, lest they find out thy boorish origin by the smell.” The American cowboys called onions “skunk eggs.”
One source suggests that smell made the leek the national emblem of Wales. The story goes that when the Welsh under King Cadwallader set out to fight the Saxons in the seventh-century Battle of Heathfield, their patron Saint David directed them to wear leeks in their caps. The usual explanation is that the identifying leeks allowed the combatants to tell friend from foe. An alternative holds that the Saxons were vanquished not only by Welsh military prowess, but by the “horrible odour” of leeks as well.
In the anonymous Philosopher’s Banquet 1633 we find the following advice:
If leeks you like, but do their smell dislike, eat onions, and you shall not smell like leek. If you of onions would the scent expel, eat garlic that shall drown the onion’s smell.
The Americans, who appear to have a law for everything, have declared that in Hartsburg, Illinois; it’s illegal to snack on onions in Cinema; whilst in West Virginia, children are forbidden to come to school smelling of “wild onions”; and not to be left out, the husbands of Alexandria in Minnesota are forbidden to make love to their wives if their breath smells of garlic, onions, or somewhat weirdly sardines.
However, in Rabbinic literature ,Ezra insisted that garlic be eaten on Fridays to encourage Jewish husbands in the performance of their marital duty.