You know, a couple of times I've seen (in published modules, nonetheless), a use of secret doors like the following:
What I don't understand is, what is the secret supposed to be? Both rooms are easily found.
More sensible is something like this:
Aha...a secret room.
This way, no matter where you're coming from, you need to do some detective work. I know that dungeons don't need realism or logic, but even so, a little bit can make the game more tangible to the players.