The great Jerry Wexler -- who produced both Ray and Aretha -- coined a great term for it: "oversouling." He described it as "the gratuitous and confected melisma" that hollows out a song and drains it of meaning.Melisma is defined as melodic embellishment. I define it as somebody who's trying to hard.
There are a ton of artists who are guilty of "oversouling" songs: Mariah Carey, Cher, Stevie Ray Vaughn, Michael Bolton, the cast of Glee, any American Idol contestant, etc. Melisma is not a bad thing. But after watching Aguilera employing it several days ago, I might just group it alongside lip-synching and auto-tuning.
Don't overdo it, friends.