I like Catsup on hot dogs and hamburgers and nothing else. Never on French Fries. As a kid it went on Scrambled eggs or in the eggs before they were cooked, yuck, kids eat the strangest things.
As far as meatloaf goes the Worscesterchire Sauce goes in the meatloaf but not on it, I just squirt a little ketchup on it and spread it very thin to give the meatloaf a nice glaze, more for appearance than flavor. Meatloaf, in my world, is properly served with mashed potatoes and gravy.