Do you ever get that feeling that you'd like to try some food that you haven't eaten in a very long time? A sudden craving to have sardines on toast, for instance? The first few mouthfuls are great. And then some circuit in your brain kicks in and reminds you exactly why you haven't eaten sardines on toast in a very long time. It's because you don't actually like them that much. This is a lesson you remember for maybe six months. Until the next craving strikes.
Another good example would be Earl Grey tea. Nice idea in theory. It's when you drink it that it all starts to go Pete Tong.