Don't get me wrong, I am not against spoilers. I think that a good deal of comic book discussion pretty much has to involve discussing what goes on in a comic, particularly if the event in the comic factors into the book heavily. To wit, while it was a spoiler, it is difficult to express displeasure with how Leslie Thompkins was handled in the Bat-titles last year without explaining what happened in the comic that got me so irritated. So spoilers have a place in discussing comics (with warnings that they're coming, though, of course).
What I don't think has a (good) place in comic discussion is the detailed plot synopsis. A plot synopsis, by itself, is a bit of a sketchy issue for me - I do them, but I try to keep it as bare-bones as possible, just so that people will understand what the heck I'm talking about when I discuss what I liked and disliked about the comic. Saying that I think there were problems with seeing Bizarro show up and kill people in Infinite Crisis #1 involves me mentioning that that, in fact, occured in Infinite Crisis #1.
But when I see detailed plot synopses out there for "discussions," it just boggles the mind. I understand there's something to be said for reading the comic for yourself, but when you have practically line for line what happens in a comic book - that's bizarre! And I struggle, really, with determing what's MORE bizarre - the fact that people do it, or the fact that other people APPLAUD them for doing it. That this type of buzz-kill discussing is POPULAR amongst a significant portion of comic book fans.
Comic discussion should be about the ideas of the comic and how well you thought the book's creative team expressed them. It should not be, "But what happened on panel 4 of page 15? You weren't specific enough! Did Character X have any lines?"
It's not the worst thing in the world (heck, if people really want to do it on the CBR messageboards, I let them do it), but boy, is it lame. And I'm just a dude who likes to discuss comic books. I can only imagine how lame it must be for the folks who actually WRITE the durn things!