TheVok:Do you visit/read/post on other online discussion forums?
I'm not sure if you're asking me or AKalel, but yes, I am and do.
There are many that are heavily moderated, especially compared to this one, so there are plenty of examples out there of how to handle a 'problem post or thread.' It's not really that difficult to understand. And yes, those forums tend to post the 'rules' up front so there's no justification for confusion.
Yes, having the 'rules' posted up front does lead to a lot less confusion, as does having the place heavily moderated.
I guess we'll have to agree to disagree, Vok. Not on the spoiler issue per se, but you seem to feel that the responsibility for spoilers rests 100% on the person posting them. I think the reader of a spoiler should shoulder 50% of the blame.
As I stated, if you (generic, not specifically you, Vok):
1. are going to a fan forum where your shows are being discussed and
2. know seeing a spoiler will upset you and
3. are not up-to-date on your show and
4. enter the forum through the 'Active Threads' link or some such equally vague portal, which you know from past experience could put you in the middle of an unlabelled spoiler thread
then:
You're an idiot and deserve to have the show spoiled for you. You should keep your whine to a minimum and not bother anyone else. It's not the end of the world... think of it as a surprise party that your boyfriend/girlfriend is throwing for you and someone leaked to you a week in advance by accident. The party will still go ahead... you just have to pretend you don't know, so smile and act surprised when the lights come on and everyone jumps up from behind the furniture.
That's just my opinion.
Anyway, it seems that I'm doing most of the yakking here... I'm growing weary of this and of repeating myself. I'm sure most of you are tired of reading what I'm saying too, if anyone is still bothering... so, Happy Canada Day everyone! I'm gonna put my red & white Maple Leaf toque on, pour maple syrup over my pancakes & back bacon and sit on my deck drinking beer all day, like the proud Canadian lout that I am. Cheers! 
P.S. WHO - Nothing wrong with fences, my friend. They keep the neighbour's dog from leaving his smelly presents in my yard so I don't accidentally mulch one when mowing the lawn.

"Something, something, something, Dark Side... something, something, something, complete!"