I've heard if a few times and found it equally annoying each of them. I remember the first time I heard it was in a travel blog by I band I used to like about, uh, ten years go? You know, soppy teenage pop - and the dude was like 'one would think that the best mexican food is in mexico, but no.'

AND I WENT FROTHY AT THE MOUTH. Until you've had at last pozole, stupid dude, you have NOT tried Mexican food.

Yeah, that's the thing, it's just from people being used to burritos covered in yellow cheese called 'authentic'. Bollocks.