Using the phrase "curdled self-pity" is marbles

Geared up and ready for the album of the millennium to drop, I'm reading the NYT review of Chinese Democracy (and checking the calendar to see if it's April 1 already) when I come across this gem of a description:

In its 14 songs there are glimpses of heartfelt ferocity and despair, along with bursts of remarkable musicianship. But they are overwhelmed by countless layers of studio diddling and a tone of curdled self-pity. The album concludes with five bombastic power ballads in a row.

What the hell is "curdled self-pity"? When does one's self-pity get so rancid that it curdles? Is the implication that one's former un-pitied self is then unrecoverable? And how does one express this in song? (Though five consecutive power ballads is probably a good start)

So naturally I had to google the phrase to see if it had ever been used before in the history of the English language. It had, once. Where else, but in a New York Times review.