Sometimes it can be a lot of fun to keep your players guessing, particularly if they’re veterans of the game you’re playing.
If this sounds like your group, bring a couple of extra books (for the same game) to every session — and choose them more or less at random.
Between those random choices (“The Big Book of Doom and Gloom? What’s that doing here?”) and the extras you bring with a purpose (as in, “Hmmm, they might take the right fork and head to Mordor”), your players won’t know what to expect.
And best of all? It’s fairly subtle until they catch on — and once they catch on, that still won’t help.
(TT is in GenCon mode from August 9th-13th. I won’t be able to respond to comments or email, but there will be a new post every day, just like always.)