> When does night become day?

My inner pedant insists: Depends how far West you are (one degree of longitude Westwards is four minutes later), and how far North (sign and magnitude are season-dependent). (See also the Wikipedia page on the Equation of Time, if you're that bored, for how noon wanders about during the year.)

Meanwhile, back at the Subject line, a judge once (approximately) said: I can't define pornography, but I know it when I see it. I think the same holds with folk music; hence the persistence and vituperation of the arguments.