What many of you don't realize is that nearly every producer uses an auto tuner to touch up a artist's vocals. You still have to be able to sing... like you have to be a GOOD singer, for an auto tuner to actually work properly. That is, unless the producer actually composes every single note and maps your voice to them. Rarely in music do you hear this.
I personally use an auto tuner when recording my music. I place my recorded vocals on a track with the plugin on it, and play them back. The auto tuner quickly shows me the places in which I made a singing error (auto tuner hits the wrong note and/or jitters), and then I record that part over, until the auto tuner picks up every single note how I intended it to.
I then REMOVE the auto tuner, listen to the vocals without it, and realize, "these are very similar; the one with the plain vocals sounds very good, but the one with the auto tuner sounds perfect." The auto tuner I use is not noticeable UNLESS you are a bad singer. Auto tuners are designed to make great singers sound even better, so their music's quality is as good as it can possibly be.