The question in the UK depends on who is answering it. To the general public, American food would not be a category as such, but would be understood as burgers and, possibly, KFC or hot dogs. Massive portions would then be mentioned. In this context, American would not be a compliment although often not an insult either. However, to the foodie population, people would lean towards California cuisine and the Alice Waters type food that is commonplace now on the West Coast and in New York. This lot would shudder at the "other" American food.