One thing that bugs me a little in my daily journey through Romanceland is the complaint about the sort of books currently offered on the romance market. Mind, I am not bothered by the complaint of the QUALITY of said books--I think a lot of the complaints about quality/editing/style/etc are more than justified. But when people say there are too many vampire books, too many menages, too many werewolves, too much gay, too much of this, that, or the other, it makes my eye twitch. When readers insist that the publishing is NOT a reader-driven market, it really makes me twitch.
I think authors are incredibly responsive to and aware of what sells and what doesn't. If people are writing, say, twincest now, it's probably because the return they see for their effort is worth it. I know I shy away from writing het contemporaries for epublishers because e-book readers simply don't want them! At first, I thought it was just a reflection on my own abilities, but my gay stories and my menage stories do just fine.
I personally do think there's a lot to the old adage, "Don't buy it if you won't like it." Why? Because authors, by and large, won't know if you like it or hate it. Authors only know the numbers on their royalty checks. And if there's a particular genre you'd like to see more of, the e-publishing world is so small that you really can vote with your dollars.