I've heard this accusation many times on yahoo, and I know a lot of people who have been to one or two foreign countries for a week in the summer to a third world country, or as a student to a university for a semester in Europe. I have wondered before in reading news about other countries, about singular incidents among groups consisting of millions of people, what if anything that really tells me.
I have also seen people come to the US to live for a while. One Bosnian christian and muslim attended my high school together in the latter half of the nineties, when people were fleeing the region. They were very level-headed people, and were friends. We (the moderate locals) were also very caring towards them, perhaps more than if they were one of us.
My question to the original postor is this: how can I, just one individual, go to a foreign country, even for a year as a student or a migrant worker, and expect to learn more about the country as a whole than if I were sitting here with all the free press and photography to choose from? As a temporary foreigner, my status is easily elevated to a role in which the government of the country I am in is restricting some areas of my travel. I am limited to my coworkers or fellow students, who by default are oriented toward my western interests, or I am travelling from one tourist trap to another and clicking my camera where the gaurds will let me. Confronted with a place like Mumbai, a city in India with over 15 million people and a projected growth by 2015 to 25 million, I find it hard to believe individual observation has any relevancy in a world of 4 billion individuals, unless it takes into account what we can learn from the written experiences of others.