After Kanye West's performance on "Saturday Night Live" over the weekend, the chattering classes are wringing their hands today over the gee-whiz revelation that, maybe underneath all that gratuitous Auto-Tune, West's voice might be a bit, as they say, "pitchy." We can go back and forth about the relative disaster-or-not qualities of his two-song set, but the hullabaloo over it begs for a few responses. First: hey, indie rockers, if you don't think that half your favorite beardo bands use things like Melodyne... But the second, and more crucial one, is this: What makes a "good" singer anyhow, and what...