1. You barely skimmed the surface of your main characters. I love to sink beneath the skin of your characters and live in their heads for the duration of the book. If your heroine has the emotional capacity of block of wood, don't expect me to care if she gets put in mortal peril in chapter twenty. At that point, chances are good I'm rooting for her to bite the big one and put us all out of our misery.
2. Every character in your book is stunningly beautiful and perfect. I have a confession to make. Stunningly beautiful/perfect characters bore me to death. If you have an entire cast of them, I'll wonder if some cruel trick of fate has landed me in the middle of an episode of America's Top Model. I was about to say the only thing worse than reading an episode of ATM would be doing a workout with Richard Simmons, but at least he makes me laugh.
And he's not afraid of sequins.
3. Events happen that go against what a character would authentically do/choose simply so you can have the plot twist where you want it to twist. This a) is lazy writing and b) assumes I'm too stupid to realize you've hijacked your characters for the sake of sticking with your outline.
4. Your main character is never in any real danger. I don't necessarily mean physical danger, though most of what I choose to read includes that component. Emotional danger works too. At some point, I need to worry the hero/heroine won't get what he/she needs. I need to be afraid he/she won't live, won't succeed, or will be broken beyond repair. If you can't deliver stakes like those, what's the point of reading the story?
5. You repeat things I already know. It's one thing to revisit an important fact/idea occasionally throughout the book. It's another thing to SHOW me a character laughing and then fill up the next two paragraphs TELLING me the character found something funny. Give me the action and trust me to understand its implications. If more explanation is needed, do it in a way that doesn't assume I'm too stupid to have figured it out on my own.
6. You rhapsodize endlessly about a certain feature on your hero or heroine. I love a sexy hero as much as the next girl. I don't love endlessly reading gooey descriptions of the hero's lips. Eyes. Jaw. Pecs. Whatever. Now, this one is certainly a matter of personal taste. I'm sure there are readers out there who enjoy having the hero's adorable cleft chin referenced on every other page. I'm not one of them. I'm much more interested in what's going on within the hero's heart and mind. And I like to think the heroine is the kind of woman who's intelligent enough to get past her initial OOOH! Cleft chin! reaction and start looking for signs of heroism beneath the external.
7. Your villain doesn't scare me. Voldemort scared me. The killer from PSYCHOPATH (Keith Ablow) scared me. A villain who has the opportunity to cause pain and uses it instead to endlessly explain his every little move (All the better to give the hero a chance to arrive, my dear!) does not. I think it's fantastic when a villain offers some sort of insight into the way his mind works. I just need it to be done in a way that increases how threatened I feel by him. If I'm not afraid of the villain, I don't care about the story.
8. If I can see a convenient way out of the danger/situation, if all the hero/heroine has to do is do x instead of y and x doesn't cost him/her anything, I'm done reading. I love to be on the edge of my seat, unable to see how the hero/heroine could either a) get out of the situation unscathed or b) pay the cost of the decision they'll have to make. You do that, and I'm hooked for life.
9. Your ending is heavy on the exposition, light on the action. This is an easy mistake to make. You've got loose ends to tie up. Questions to answer. A foundation for the next book to lay. I get that. But I've been reading feverishly for the last two hundred odd pages to get to this point and I don't want to sit back and read the equivalent of Driving Miss Daisy. I want action. Danger. Life-threatening/emotionally-scarring stuff. I want to be unable to put the book down because I'm so afraid the characters I know and love won't come through.
10. Your stakes suck. For a story to really pull me in, the stakes have to matter. Really matter. I have to care deeply about the characters and the outcome of their struggle. I have to want them to make it. I have to see that the cost of them not making it is painfully high. It doesn't actually matter if the stakes involve physical danger, saving the world, or finally making a romantic commitment to their soul mate--the stakes have to really matter to me. For the stakes to matter, you have to push the characters to their limit. You have to make me frantically turn page after page because I have this terrible fear that somehow the characters won't pull it off.
Any reasons you'd like to add to the list?