My only problem with that is that I know I will invariably read any sblock, any I strongly suspect I'm not the only one.
With haunts specifically half the fun of them is that those that only effect a single character are bizarre and there is often a way for characters outside to effect them that would be far easier to determine if those outside were to.
I would really prefer some kind of private tag, but there does not seem to be one... I believe I will start placing Knowledge checks, etc., in such sblocks though as they are generally speaking quickly shared with the party in any case - like jkason says. I don't want to start speaking for characters though.