Just as "It was a dark and stormy night" is reckoned too cliched a beginning for any piece of serious fiction, there are a growing number of tropes that, while once original and startling, have become sources of predictable eye-rolling among readers.
I was reminded of this when I saw a post on Facebook by mystery novelist Sandra Parshall, who lamented "I've just finished yet another crime novel in which the supposed big twist near the end was the revelation of a secret sibling, somebody whose existence was previously unsuspected. (But this time I saw it coming from the second the character was introduced because the author practically put a flashing neon sign over his head.) This is the fifth or sixth newly published crime novel I've read in the last year with this "twist." It's getting tiresome. Why is this hackneyed plot device showing up so often?" The funny thing was that I had just finished my perusal of a chapter in one of my students novel -- and I'm pretty sure there's a secret sibling plot twist brewing. If she can turn it around so the (presumed) secret sibling isn't, well, now that would be a good twist.
A related and even more embarrassing plot twist is the evil twin. I blush to say I used this soap operatic device in my very first (mercifully unpublished) novel. And there's the long-lost lover/spouse/relative who suddenly appears -- often in disguise -- and upsets the order of things. That goes back as far as Homer's Odyssey -- if not farther. In my Elizabeth books, I left open the possibility of her father showing up, or even Sam. . . though I never thought too hard about the latter. I'm sure there are other plot devices that some find way too predictable -- are there any that annoy you?