While I don't want to defend American cheese, I take some offense to the broadness of that statement. In many places, Americans care dearly about sourcing, and you can get very high quality cow/goat/sheep milk. Pasteurization could be one thing, but I think the diet is key. Here in California, our milk varies significantly in flavor from winter to summer because we have a Mediterranean climate with no rain in summer. Our eggs also undergo a change - chlorophyll from the green grass makes the yolks much more orange in the winter and spring, and then they gradually get more yellow over the course of summer.