I don't know if this has been addressed or not, but I think the addition of the realspoiler tag is a bit of a bandaid fix for the "boy who cried wolf" situation with the spoiler tag. While I don't think it's a bad idea for having a tag for minor spoilers and a bit of playing around and another for big nasty spoilers, i do feel that the same thing will simply happen to the realspoiler tag.
How about it becomes a jailable offence to misuse a real spoiler tag, to deter the same thing that happened to the spoiler tag, happen to the realspoiler tag. Do we really want to need a totallyrealspoiler tag?
Also, I don't know much about the code behind the forums, but would it be that difficult to do a bit of PHP hackery so that when someone is jailed, spoiler tags are preserved? I'm guessing you would need to use some pretty nasty hacks, but I think it might be something worthwhile.