There was a time when television networks were terrified of period pieces. The conventional wisdom was that TV shows set in the past were a tough sell and drew disappointing ratings. However, recently cable networks began to hop on the period-drama bandwagon. HBO had “Deadwood” and “Rome.” Showtime ushered in “The Tudors.” And AMC hit it big with “Mad Men.” Now period pieces are a popular programming pick, from HBO’s “Boardwalk Empire” to ABC’s “Pan Am.”

But not every period drama deserves raves.