LA CUISINE French Chic Country KITCHEN Fat Chef Sign
LA CUISINE French Chic Country KITCHEN Fat Chef Sign
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Why are French words often used in association with expensive and fine quality and sophistication?

Food and cooking, fancy restaurants and banquets:
chef, cuisine, entree, escargot (snails), hors d'oeuvres, maître d'
French names for wines

chic, petite, suite, valet
many other words and phrases

Because France is renowned for having a refined cuisine and nice fancy restaurants.
Also, many words used in food and cooking just don't have an English counterpart because they are products used in French cooking (escargots, filet mignon, gratin, etc.)
The French are also famous for being romantic lovers (fiancé, rendez-vous, etc).

That's really a question of reputation though.
In French we use a lot of English words too, mostly when they define products invented by the American (chewing-gum, cheeseburgers, for example).