The thing is, the same music technology that makes auto-tune possible allows us an unprecedented ease of recording. I don't quite buy the idea of 'only having half an hour in the studio to get it right': digital recording means that, provided you have a high-quality mic, you can record a vocal pretty much anywhere (especially if it's a backing harmony), anytime.

If a harmony was hideously off, I'd simply junk it and re-take it. If it was only slightly off, it'd probably actually be useable. And, to prove I'm not a luddite, I suppose I'll concede that if I was engineering a big-budget album, say, and I knew a backing vocal was going to be low in the mix, I might use a bit of auto-tune. But I can't help but think that if I was this hypothetical sound engineer on this hypothetical big-budget album, I'd probably have the studio time to get the singer to do a second take.