On Prologues

I seem to be reading a spate of books of late that have completely pointless prologues. I realize the custom in the suspense genre these days is to open with some poor innocent being captured or killed by a serial killer so that we can see just how deviant the "baddie" is (or so the author can then relax a little, having already shown you the basic plot and stressed you out) and I've gotten used to that. I've even written a prologue for my romantic suspense, though it's not nearly so involved as some. (I posted a draft of it a while back, here, and while it's undergone some revisions since then, it hasn't become much more elaborate.)

I didn't have a prologue at first, but as I wrote, I realized that I wanted the reader to know that Nicole was dead long before the characters became certain of it. I wanted them looking for clues before the characters did, and that was the sole purpose of the prologue.

But the past few books I've read, I wonder why the authors bothered with the prologues and why no editor told them the book would be stronger without one.

• In one case, the prologue--which occurs more than a hundred years before the rest of the book--shows the discovery of an archaeological find. One of the artifacts is stolen later in the book, which forms the basis of the mystery/suspense, but nothing dramatic happens during the find, nothing vital that is not explained more than once later on in the story.
  
• The prologue of another book, taking place nearly ten years before the rest of the story, depicts the main character witnessing a murder as a child. The event is definitely life-altering, and you do need to know about it to understand the protagonist, but it's recalled so many times in the book, in dreams, in discussions, etc, that I got bored with all the repetition.
• The third actually takes place after the book begins. That is, Chapter 1 is dated earlier than the prologue. You get the prologue again later on in the book.

None of these is unique to the book in question. I've seen all these techniques used more than once (and the list is far from complete--certain styles of prologue get used regularly). However, reading these three books one right after another really brought question of a prologue into focus for me. All these books are by "name" authors (I'm too lazy to see whether they all qualify as "best sellers"), who've been writing and publishing for years, and now I want to go back and see whether they've always incorporated these introductory bits with information readers get again later on, or whether there's some sort of trend that's making them feel they need to have them.

I am a careful reader, so if I get information in a prologue, I don't want it again in the body of the book. If characters are going to discuss in detail a crime that's taken place, I don't need to see it being committed--you don't have to show the blood spilling first if you're going to give me two pages of spatter analysis later on down the road. (On the other hand, if you do show the spillage, that's fine...just give me a single sentence about what the spatter analyst had to say when the time comes.)

On television, there's a minute or two of story before the titles roll. Often, in shows like Cold Case, Without a Trace, Criminal Minds, the crime takes place in that first spot, and the rest of the show is an investigation into it. Sometimes, further crimes take place during the show, but there's a teaser up front, and that's how I often feel about the prologues in suspense novels. Maybe that's actually why I don't even notice the "serial killer grabs a victim" prologue any more; I'm so used to it from television.

So I wonder...how do the rest of you feel about prologues? Do you have particular types you like or particular ones that make you crazy? And what about epilogues, while we're at it?