Crossing genres and pissing readers off

Sometimes these two items walk hand in hand. The cause-and-effect can leave a nasty little taste in the readers' mouths.

When a reader picks up a romance...they want happily-ever-after.
When a reader picks up a thriller...they want a nice game of cat-and-mouse.
When a reader picks up a horror...they want nightmares.

A reader will know what they want when they pick up the book. Books that cross genres are subject to being tossed at the wall and generally defamed and defiled on Amazon.com discussions--IF the reader does not receive what he/she expected when he/she picked the book up.
There is much of a fuss about J.R. Ward's books. Some, okay many, say that she's gone the way of dark, urban thriller type. Some readers don't care for the graphic sex (and sometimes a little bdsm) that goes with the story. And I will readily admit that her HEA's are a bit iffy.
SPOILERS!!!
RUN...DO NOT WALK...SCROLL DOWN UNTIL AFTER THE CAPS...YOU'VE BEEN WARNED!
I'm picking on J.R. for one reason. I read her books. In fact, my dearest one gave me the entire set for Christmas. heh
Okay. I'm simply saying that a ghost/vampire relationship can be a bit iffy. I can understand Rhage's story because Mary can't have kids. It was sort of a trade-off for the Scribe Virgin.
No problem.
I loved Butch and Marissa's story. Even with the homosexual overtones from V. *shrug* No big deal. Then we have Phury and his multitude of Chosen Ones at his house. Lord love the man. Or pity him. Too bad he gave up the red smoke, huh?
Now.
To Rhev. And the Princess. And all the sick, twisted shit she makes him do to get off. The scenes are graphic. But I know it's not about love/sex. It's about control. They fight for it. And it can be pretty fucking ugly.
Sometimes I wonder if J.R. has let the romance go a bit in order to go darker with the BDB's stories. I've hung so far because I have time invested in the Brothers. They are as real to me as my own characters. I haven't quite reached that point where I will call it quits and look for someone else to appease my Paranormal Romance wants.
Not. Quite. Yet.
BACK TO THE GENERIC STUFF...
Stephen King writes horror. Though I wager some would be surprised at the romance in his books. Yeah, I said it. ROMANCE in a Stephen King book. But that's extra. I read his books to savor the magnificence of his storytelling. I don't look for a HEA. In fact...get this...he LOVES to kill off at least ONE major character. He does it all the time. But I take that with a grain of salt because I know I'm not reading his book for warm fuzzies.
So I offer up a bit of a warning here. Be careful if you try to cross genres. It's kind of like Ghostbusters (Yeah. I'm pulling an eighties movie out of my mind vault. So when you find yourself humming the theme to "Ghostbusters" and craving marshamallows later...don't blame me.). If you cross the stream...you don't know what you're going to get.
Please...for the love of GOD...do NOT tell me it's a romance if it's not. Don't lead your readers to your book with promises that you can't or won't keep. There's truth in advertising. Believe me.
Your readers will thank you for it.
Grins*
ADDENDUM: I don't want to come off like I'm saying that crossing genres is bad necessarily. But it's when you deviate from your original genre and spiral toward another...you can keep your balance, or you can forsake what brought readers to you in the first place. It's a consideration.