In yesterday's thread about my D&D campaign, Dàchéng asked: "You mention twice the Kobolds' lair, though your players weren't in the least interested in it. Might you be using this blog to influence your players' decisions out of game?" Direct answer is no, I know that half of my players don't read my blog (remember my campaign is in French, but the blog is in English). But there is a reason why I mention the possibility of the kobold's lair turning up again: The double opt-out principle of adventure building.
The idea is that if the players come to a fork in the road with one way going to the Caverns of Doom, and the other to the Pyramid of Curses, chances are that their decision on where to go is relatively random. Maybe just the priest hoping for undead in the pyramid, against which he is extra powerful, and persuading the group to come along. The decision does not mean that the players are necessarily not interested at all in the Caverns of Doom. Thus in an adventure like that, I would always put another story hook somewhere later leading the players to the option they decided against. If they still don't want to go, chances are that they really aren't interested. But by giving a second reminder of the other option being there, and maybe some more information what to expect there, there is also a chance for them to decide that they actually would quite like to go there.
In a way that is a compromise between making adventures more or less linear and forcing the group to visit every encounter the DM prepared, and making adventures completely sandbox where the players skip half of the encounters for no good reason. The players aren't forced into anything, but they need to opt out twice before the DM throws his carefully prepared encounter or dungeon into the garbage bin.