"fair to middling" の定義と意味

What is the origin of the idiom "fair to middling" and when to use it?

The idiom "fair to middling" originated from the grading system used by farmers and merchants to label the quality of agricultural products, particularly cotton. The grading system classified products as "fine," "good," "fair," "middling," and "ordinary," with "fair to middling" representing a moderate level of quality. Over time, the phrase transitioned into everyday speech, coming to mean "average" or "slightly above average" by the 1860s.