A fastidious person is difficult to please. They are careful about very small details and insist that attention be paid even to small matters so that things are perfect. A person fastidious about appearance pays attention to the appropriateness and tidiness of clothes. When you are fastidious about doing something you plan it perfectly and see that nothing is overlooked. You are fastidious about food when only what you think the best satisfies you. (Image from Gino Barasa)It is a unrealistic fear, or downright meanness.