Ga Chicken Mom is right on the money on Fair to middling"
This excerpt is taken from the following site.
It has many more curious phrases like this as well.
http://www.word-detective.com/080401.html
"It's not "fare to Midland." It's "fair to middling," meaning "moderately good," "OK but not great," or "so-so." If someone were to ask you how your vacation at your in-laws in Pittsburgh went, you might well say "Fair to middling."
We all know what "fair" in this sense means: it's midway on the scale from "good" to "poor." It's that "middling" that is a mystery to many, if not most, people, but it's really quite simple. "Middling," which first appeared in English in the 15th century, is an adjective that denotes something that sits in the middle of a range of quality. Wheat, for instance, was once rated as being "fine," "middling" or "poor."
"Fair to middling," which first appeared as a phrase in the mid-19th century, thus really means "fair to fair," a little joke in that the range between the two qualities really doesn't exist. "