Do NOT use the ketchup in Mexico.
... Why not? I like Mexican ketchup.
I had some from their food stands and I was all water down and it tastes disgusting to me. (I don't know about the big chain restaurants there, I'm assuming it's the regular ketchup.)
Well all the places I've had it in Mexico (which isn't many since I don't put ketchup on Mexican food) but they all seemed to have the same kind. It's cause the tomatoes in Mexico aren't all modified like American ones. So to me it tastes more natural.
And hey, don't judge a country's cuisine by a food cart.
My family lives in Mexico, we stay down there every summer and the ketchup always is watered down or bitter to me. But that's just in my experience.
I threw up from milk in Canada.
They keep it in bags there O.O
They pasteurize milk differently (or not at all) in different places.