6. The character is a love interest that doesn’t have a role outside of romance. She’ll probably be a more interesting love interest if she has something else going on. For example, Lois Lane is (occasionally) a competent reporter whose investigations sometimes tie into Superman’s work. Pepper Potts figured out who kidnapped Tony Stark by breaking into Stane’s office. Ramona Flowers from Scott Pilgrim had a penchant for awesomeness and a mallet. Also, she was a ninja courier for Amazon.
6.1. The character is defined by her physical attractiveness and/or sex appeal. If you were listing the three most important traits of a major character and physical attractiveness happens to be one of them, I would recommend rethinking the character’s development because most likely the character is a love interest that is interesting only to the author. (Think back to #1–you wouldn’t want to read about a guy whose main trait was his handsomeness, would you?) Also, please bear in mind that most of the professionals evaluating your submission will probably be ladies, so you won’t even have the titillation angle working in your favor.
7. The character has no substantial goals besides going along with other characters and/or getting in bed with somebody. If you’re going to bother writing in a character, I’d recommend giving him/her some sort of independent effect on the plot. If not, why bother having the character? Fortunately, you don’t need to give a character much space to give her/him a role to play. For example, Neville Longbottom had maybe 30 lines in the first Harry Potter book and he still managed to raise the stakes for the protagonists by growing a spine at absolutely the worst moment. (Dumbledore’s recognition of his badassery was probably the highlight of the first book for me).