A coated smooth surface of a substrate repels liquids and viscoelastic materials and can have anti-staining and anti-biofouling properties. The smooth surface can be coated by applying a chemical layer on the surface and a lubricant. Such coated surfaces are useful for use in toilets, urinals, or other devices for the processing of liquids and viscoelastic materials such as solid or semi-solid metabolic waste of human digestive system. Such coated surfaces can also be applied to windows for buildings or vehicles such as automobiles or camera lenses to repel liquids (e.g. rain), ice, frost, insect residues, and birds' feces.