Re: Writers' Guild of HPCF
I don't think so. As long as you know the audience you're writing to and you're consistent in each individual work you're writing then mixing genres can be a great way to create new and unusual ideas.
The only thing I'd say is make sure you don't leave the reader confused. Don't throw in elements of other genres just for the sake of having them. They need to make sense in the context of the story you're writing. As long as that happens then you can do what you like. That's the great thing about writing.