Hey, it looks like LJ actually added a genuinely cool and useful feature for once! Let's try out the new spoiler cut tag!
[Spoiler cut with no spoilers behind it!] OK, well, that works, but there's no way to end the cut, so you can't have no-spoilery stuff after your spoiler cut. And after a bit of fiddling around, I've detemined that if you don't put a line break after the cut, like, say, if you want to cut off the end of a sentence, then it will lose all your paragraph breaks after the cut sometimes do strange, random things to your formatting and line breaks that aren't nearly as consistent as I thought they were. Sigh. Even when they try to give us nice things, they're not always very good at it, are they? Oh, well. It's still potentially very useful.
ETA: Oh, wait, I managed to get the end tag to work. I think. Let's see...