Perhaps this season’s silliest – and most unintentionally revealing – episode of “Glee” came last month when singing student Sam pretended to be his slicker, smarter (and nonexistent) twin brother.

Glee wasn’t known for its country music covers. Throughout the show’s six-season run on Fox, the ensemble cast of Lea Michele, the late Cory Monteith, Matthew Morrison, and more tended to lean their ...