Everyone has three bullshit detectors; the head, the heart and the gut. John Ralston Saul broke these down further in On Equilibrium: the head (reason and common sense), the heart (ethics and imagination) and the gut (memory and intuition). I prefer to reduce his complexity somewhat. Besides, three is a good strong number.
An interesting experiment in the Netherlands seems to show that high-cost decisionmaking works better when we sleep on it. If the brain alone is allowed to wield too much control, it tends to overanalyse the problem, resulting in poor decisions. Another important prerequisite is that the decisionmaker must be aware of the choice in order for the bullshit detectors to work properly.
The upshot of all this would be that complex questions should not be answered the same day, if one is to maximise one's critical faculties. Read more about the experiment here.