But, on occasion, Aguilera would have moments when she took after contestants in a way that was not constructive, it was just obnoxious.
And while fellow judges Adam Levine and Blake Shelton have some of the best chemistry on television as they playfully argue and snipe at each other, Aguilera didn't get how that worked. Whether she intended it or not, she came across as mean-spirited.
It wasn't always as bad as when she went after her former "Mickey Mouse Club" castmate Tony Lucca in Season 2, but it was sometimes pretty bad.
Now, she seems to have figured it out. She's better at criticizing without being personal and nasty about it. She's better at kidding around with Levine and Shelton without making it all about her.
What happened? What turned her around?
Whatever it was, it must have been relatively recent and sudden. When she appeared with Levine, Cee Lo Green and host Carson Daly at a news conference shortly before Season 5, she could not shut up. She talked endlessly and answered questions that weren't asked of her.
Maybe she watched Season 4, when Shakira sat in the seat Aguilera occupied from Season 1-3. And Shakira did a great job — she had a lot of cogent things to say and she was actually likable.
"She did a beautiful job — just sweet, lovely energy, and lovely for the show," Aguilera said, insisting she hadn't actually watched Season 4.
Maybe Aguilera noticed that Levine and Shelton have pretty much become the stars of the show. And that by arguing with them in a way that seemed, well, real, she was making herself look bad.
Maybe she noticed that Levine has a development deal with NBC and is developing a sitcom for that network. (And, according to People Magazine, he's the sexiest man alive.)
Shelton has done specials for NBC. Green seems to appear every time he possibly can with the network, and he signed a development deal with NBC.
What Green contributes to "The Voice" is debatable. What Aguilera contributes is much more viewer friendly than it used to be.
Scott D. Pierce covers television for The Salt Lake Tribune. Email him at firstname.lastname@example.org; follow him on Twitter @ScottDPierce