Bon jour, Miss Snark!
You recently said, "This is going to be a VERY hard sell to an agent. Unless your agent called it a romance when it was a Western, it's going to be really hard to find someone to take this on."
Is it customary to discuss with an agent HOW they're going to pitch a book? I had a friend who learned her agent was pitching her project as a middle grade book when, really, it was a teen book (due to subject content). She wasn't very happy (the book never sold). Should she have trusted the agent's vision of the book or should she have corrected the agent's pitch?
The day my clients start "correcting my pitch" is 30 days before they get a new agent, and I'll be happy to waive that by fedexing a release this very day.
My clients have a hard enough time picking the correct category for their novels without trying to figure out how to pitch it. Fortunately we have a division of labor here that works well: they write wonderful books, and I figure out how to sell them.
The reason I'm waving my arms in the air and howling about this is cause 99% of the authors I know do NOT know how to position or pitch a book to an editor. Your friend is a CLASSIC example. YA and middle grade do NOT divide based first on subject matter. First it's vocabulary, sentence structure and tone. You can have middle grade books with very difficult subject matter but not written with YA vocabulary. And you can't sell middle grade vocabulary to the YA market.
My comment about romances and westerns was mostly for illustration. I've had some clients with oddly checkered submission patterns and taken them on cause I thought the book could be pitched in a new way. I've done this only twice, and both were as favors for long standing well established industry friends/colleagues. If these exact same books came over the transom I would have said no. Neither sold on my pitch either.
I've also repositioned novels after a round of rejections but that's mostly calling something a thriller rather than a horror novel to expand the pool.