Good soups have specific ingredients that make them good. They are also cooked a specific way to bring out the right flavors and textures. A bad soup has the wrong consistency, flavor, ingredients or cooking methods. If just one of these is wrong, an otherwise good soup can fall short.
Every good soup starts with a good stock. Meat, meat bones, vegetables and seasonings boil in water to bring out the flavor. The resulting water is soup stock. The type of stock for a soup depends on the type of soup. For example, if the soup is chicken noodle, it requires a chicken stock. The type of soup also dictates what seasonings will go in it, such as bay leaves for chowder.
Without the right ingredients and preparation, a soup may have the wrong thickness and consistency. Stock is watery when it is complete. Stocks for soups that have watery broths, such as chicken noodle or minestrone, have the right consistency without anything extra. Creamy soups, such as creamy chicken noodle or creamy tomato, need cream and sometimes butter to give them a creamy consistency. They should be creamy and smooth, but not too thick. Thick and creamy soups, such as baked potato soup and chowder, need cream, butter and flour to give them the right consistency. The flour and butter must be a roux before it goes in the stock.
A good soup always has good flavor. It is not too salty or overpowering and it does not have uncomplimentary spices. A soup that needs a little salt or pepper is not necessarily bad, as diners can add their own at the table. However, a cook can only fix a soup that has too much seasoning in the kitchen. If it reaches the table in that state, it is a bad soup.
A good soup has fresh and correct ingredients. Using the wrong ingredients can make a soup too watery, thick, oily or bland. Frozen vegetables can substitute fresh vegetables, but it is not ideal. Heavy cream is best for creamy soups and chowder. Good soup has real butter rather than margarine. Fresh meat and vegetables goes into good soup stock, not base or bullion.
The texture of a soup depends on the vegetables and meats in it. The meat in a good soup is tender. The vegetables should be soft or al dente, according to taste. If soup meat is too dry or vegetables too crisp or soft, it detracts from the overall effect of the soup.