“I open the door, duck under the poisoned blade trap, step on every third brick, and make sure not to trip the hidden laser sensors.”

If you’re using a pre-packaged adventure, it is possible that some of
the players have already seen it, or even played through it. (If you’re
really unlucky, one of them GMed it!) As soon as you get a hint that the
players are acting from knowledge that they, themselves, should not
have, it’s time to throw them a curve ball, such as an unplanned
encounter, a room that “shouldn’t” be there, or a trap they weren’t
expecting – and, perhaps, to re-evaluate whether you want to be gam-
ing with people who are willing to cheat at the expense of everyone
else’s fun. Or at least yours.
Predetermined bonuses and worst-
case reactions (e.g., “never any worse
than Neutral”) are possible for unusu-
ally friendly NPCs.