Pet Peeve #1:
The term "pet peeve". I have disliked it since the first time I recall hearing it. I'm not sure why (or why I still use it on occasions such as these...). The same goes for "fav" or "fave" instead of "favorite" (though in the time of Twitter, one may be excused for using the abbreviation under duress-- stupid 140 character limit!).
Pet Peeve #2:
Introductions (or cover/jacket-flap blurbs) that give away the story (in a book, but spoilery blurbs on DVDs are just as annoying). Personally, I've rarely read an introduction that didn't give away something-- and frequently, everything-- so why do publishers insist on putting them at the front of the book?! These days, I know enough to carefully skip introductions, so I'm safe-- but it's still irritating. Maybe they think that so few people actually read introductions that it won't be a problem, but in that case, why bother with them at all? It feels more like they assume that you've read the book before-- a dangerous and baseless assumption. Either that or they delight in ruining things for other readers.
It's a temptation: "Hey, you! Yeah, you with the book! I know you're a reader. (You've got a book in your hands right now, haven't you?) I know you're the type who'll read anything-- cereal boxes, toothpaste labels, even the occasional piece of junk mail. Why not try a nice, juicy introduction, eh? {sly smile} What's that? Spoilers? No, no, nothing like that here. What, you think we'd be rude enough to put spoilers in an intro? What kind of sense would that make? No, I assure you, you're safe reading this one. In fact, if you don't read it, you'll be missing out on all sorts of relevant information about the author's history-- things that would make reading the novel so much richer an experience. Here. Why not just try the first paragraph? If that one turns out ok, you can read further..."