Srsly, would it kill you?

I spend a fair amount of time reading books about writing. I try to balance this with actual reading (of the fiction variety) and writing, of course, but I find most of the books helpful, so I read them. And while I find many of them helpful, there is something that irritates the snot out of me.

Attn: Writers of Books For Writers:

When using examples from fiction, would it kill you to offer a heads up that there's a SPOILER coming? Srsly?

Sometimes it's necessary to give away the ending to a story in order to make your point, but if that's the case, would you maybe be a dear and say "Spoiler Ahoy!" so that perhaps I can mark the chapter and come back to it after I've read the story in question? Of course, one should expect a writer to be well-read, but the fact is, it's impossible to read everything. There may be some classics left that one just hasn't gotten to yet. In fact, I've had several "classics" spoiled for me by reading such writing books. The same applies to films, which are also often cited in these books.

Thanks to all of my reading on the subject of writing, I now know the endings to "The Notebook", "Anna Karenina", "The Bourne Supremacy", "First Blood" (aka Rambo, and no I had neither seen nor read it), and several Hitchcock films.

I'm not asking any of you to stop using examples from film and literature. Quite the contrary. But...would it kill you to give a little heads up BEFORE you tell me that the ship sinks at the end of "Titanic"?