The Washington Post has a cute article: The Moby Equation. A helpful sellout guide, taking into account rock and roll ideals, the song's sacredness, the artist's reputation, wealth and time since their heyday.
These days with a PVR and downloading TV from the Internet, television commercials are alien to me. The idea of a song being "wrecked" by a commercial seems like a thing of the past, but I'm often weird about these things.