Why are TV singing competitions still popular? Why do they continue to proliferate? Why does Christina Aguilera stlll have a job as one of the judges on The Voice (7 pm., NBC/Ch. 5), which returns tonight for its third season?
I don't know what the answers to the first two questions are. But the answer to the third question is pretty obvious.
It's the Paula Abdul factor. Watching Aguilera is like watching Abdul when she used to be a judge on "American Idol." You know there's going to be a train wreck eventually.
Elsewhere on TV ...
NFL: Cincinnati Bengals at Baltimore Ravens (5 p.m., ESPN); San Diego Chargers at Baltimore Ravens (8:15 p.m., ESPN)
Bachelor Pad (7 p.m., ABC/Ch. 4): A winner is declared in the season finale.
Hell's Kitchen (7 p.m., Fox/Ch. 13): A winner is declared in the season finale.
The L.A. Complex (7 p.m., CW/Ch. 30): Nick gets fired.
MasterChef (8 p.m., Fox/Ch. 13): A winner is declared in the season finale.
Warehouse 13 (7 and 9 p.m., Syfy): A pill is making people taller.
Major Crimes (7 and 9 p.m., TNT): A kidnapping case puts extra pressure on the squad.
Perception (8 and 10 p.m., TNT): Pierce is tipped off about a conspiracy to cover up the murder of a U.S. Senator.
Switched at Birth (9 p.m., ABC Family): Regina's impulsive wedding upsets both families.
Great Performances at the Met (10 p.m., PBS/Ch. 7): Behind the scenes of Robert Lepage's staging of the four-part ''Der Ring des Nibelungen'' by Richard Wagner.