I think most American foods are very good, even if they're usually high calorie. I always gain weight when going to the USA. What I don't like that much about their food is that often times, even dishes that are savory contain sugar, sometimes significant quantities. With pork meat, that's actually not bad taste wise, but I really don't like sugar in things like beef stew. Or sauces.
Peanut butter and jelly is something that I wouldn't even try. Sugar, fat and starch. I'm fat enough as it is - why the hell would I eat something like this ?
Something else I absolutely abhor about American food, or more precisely drinks, is the tendency to drink out of paper or plastic. I refuse to drink out of paper and plastic. On my first cruise, I learned that drinks on the pool deck are served in plastic or cardboard to avoid injuries from broken glass. While I applaud the precaution, I haven't been back to the pool deck for drinks, ever. Drinking out of plastic or cardboard is something so disgusting I keep wondering how people have come to accept it. The cup becomes slippery from the condensation or too hot to touch (don't even get me started on those flimsy handles they sometimes have or used to have) and has a distinct wet cardboard odor. Horrible stuff.