When we were in Florence, that gelato I had for the longest time was in my opinion the best gelato I've ever had in my life. Frozen nectar of the gods, I used to say. But now as I look back on it, given where I was (Italy), who I was with (my SO), I could've been eating a slushy 7-Eleven Slurpy with a fork and I would've declared it the "best gelato ever!"
I sort of feel the same way now about other things I've thought were the best ever, like that baguette we had in Paris, or the paleta I had in Mexico City, or the molletes in Puebla, etc.
Maybe all those "best ever" moments were really the result of being in an exotic land (for me) with someone whose company I really enjoyed.
Now, granted, there are certain foodstuffs that are in fact sort of better in their indigenous land. Montreal bagels, NYC-style street pizza by the slice, Taiwanese stinky tofu, seafood in Hong Kong, etc. all come to mind.
And, some of those things are better "over there" simply because of a matter of geography (Hong Kong just has more access to fresh seafood, for example) or muncipal regulations (stinky tofu in Taiwan is just stinkier because brine is allowed to fester like a bad science project petri dish).
But I am beginning to think that alot of what we fondly remember as "the best ever ___" is really a product of our imagination, prompted by circumstances, and not so much a product of the actual food.