|Original Art by: MolinGirl @ DeviantArt|
Whatever genre-mash is concocted, I've a Super Big Rule as a writer and Top Demand as a reader:
The novel better deliver on the marketed genre's expectations.
Your friendly Word Whores have written about those expectations before, so I won't rehash them. Sure, retailers ultimately decide where to display/list the book. However, as an author, I better be able to succinctly answer the most common question put to writers, "What kind of stories do you write?" "Plot Stew" is not an acceptable answer. "I write a little bit of this and a little bit of that," isn't going to help sell your book. You need to be able to say, "I write High Fantasy Mysteries" or "I've published a series of Amish Space Westerns."(hey, the latter could happen, right?)
If you're going to mix genres, do it well and do it for a reason. Tossing assorted genre tropes into your story may give you a lot of rope for creativity, but you're tying your hands to the expectations of readers of those genres.
Be mindful of the marionette.
It doesn't entertain when it's tangled.
Image Found Here: http://molingirl.deviantart.com/art/Tangled-Strings-406032995