1.) Rhyming couplets/picture books in verse
It’s not that books in verse are inherently bad (and of course I’d be open to seeing more books from published poets), but that it’s very common for me to see picture books in rhyming couplets that lose their plot and narrative structure in order to make the rhyme scheme work.
“I’ll tell you the story of Prue,
You won’t believe that it’s true.
She had a hat,
But it wasn’t just that.
She loved that her hat was blue!”
But those 29 words could have gotten the same point across with five in prose:
“Prue loved her blue hat.”
And in a picture book, where every word is precious, there isn’t really room to meander when we’re trying to get a full narrative arc in under or about 500 words.
2.) Needs a fresher take on a common theme
The market for bedtime books, new sibling books, holiday books, etc. is so competitive and a lot of publishers have covered this territory many times over with both original books and licensed characters. So while I read a lot of very sweet submissions on these themes, it’s hard for me to envision where there’d be room in the market without another hook that hasn’t been seen before. (I don’t have an example here because frankly, if I had a brilliant fresh take off the top of my head right now, I’d probably try and write it myself! But you can also look at 9 Factors of a Successful Picture Book for some ideas of how to make your child-friendly/relatable theme stand out.)
3.) Passive characters
I see so many picture book submissions where the child character doesn’t solve their own problem, and that is problematic in today’s picture book market. Picture books today are to help the young reader realize that they have agency to change things or do things for themselves, and so when someone acts as a ‘fairy godmother’ (usually it’s a parent or friend in this role) for the protagonist, the main character loses that chance at growth – at figuring out how to solve their own problem after a series of trial and error that ultimately led them to the answer. (For more on this, you can see my post on traditional picture book structure.)
I hope this helps as you write, revise and/or query your picture books!