One thing that affects perception of flavour more than anything else is how hungry and thirsty you are. Not that the orange juice in Marrakech isn't great (I've had it), but if you're really thirsty whatever you drink is going to taste amazing. Same goes for being really hungry and food.

What's interesting is that these perceptions persist even when you have those foods again. Having been exhausted and very hungry once and having had fish & chips afterwards, that flavour (of fish 'n chip-shop deep fried cod and greasy chips) still knocks me over every time I have it.