"Better Than Revenge"
The telling lyrics: "She's not a saint / And she's not what you think / She's an actress, whoa / She's better known / For the things that she does / On the mattress, whoa."
Who it's supposed to be about: Camilla Belle
Why? Swift was candid about Belle coming between her and Joe Jonas, and the pointed lyrics about an actress (see above) and her love for vintage dresses make it clear that this song is about Belle.