Clearly, Adele is not a singer who requires Auto-Tune and it would be a sin and a shame to subject her vocals to that kind of mangling. She is also a singer who plays with pitch. Some vocalists are spot on each and every note. Adele bends and sways. It's part of her artistic character and a strong reason to like her work.
But when you play with pitch, you're also playing with fire. What sounds like musicality, texture or even emotion to one person can easily sound like out-of-tune to another.
So here I think we have an example that is right on the edge. The notes are bent right to the limit of what could be considered artfulness. But have they gone too far for some listeners?
Here is the video. The line in question is repeated several times during the song, at 1.31, 1.44, 2.35, 2.48, 3.51 and 4.04 with the lyrics, "We will stand tall".
Now to my ears, there is something not quite right with this line, at least not on every delivery. The fourth repetition in particular seems rather jarring. I might also say that the 'll' of 'tall' seems rather to have been lost, but that's a different issue.
I'm not going to say that there is a right and a wrong here. I will say though that when I first heard the song, on TV, this line made me prick my ears up. For me, it's hovering on the borderline between OK and, "Can we punch in on that?".
But that's why we have producers - to make these kinds of decisions. That's part of the art and the satisfaction of recording production. And much more satisfying than reaching for the Auto-Tune!
P.S. Adele probably did more for music in the last five minutes than I've done in my entire life, so absolutely no disrespect is intended. But can we, er, go for another take?
P.P.S. Here's the waveform of Skyfall. Mastered or what??