I had never been to a McD's overseas until I was on a trip with a coworker without much exotic eating experience -- he got seriously ill trying to eat both south american and middle-eastern fare, so he now sticks to McD's and such when on travels.

I was on another mission with an older gentleman who had traveled the world extensively, but he said after about 50 his GI tract just stopped being able to handle the variety (and sanitation), and the ubiquitosness of McDonalds and other fast food places was the only reason he could still travel, so he understands why people don't like them but he'd be stuck at home (or carrying his own food) without it.