This is a kind of reverse psychology question. You might as well just ask, "What do you think a great user interface looks like?" But the trick is not to make the question too obvious so the prospective designer does not give a general answer.

By describing elements of the worst ever user interface, the designer illustrates his or her design values for such things as buttons, input boxes, labels, login screens, as well as shapes, sizes, positioning and colors of these elements. A professional UI designer should always give a detailed explanation of why a certain interface has no chance of pleasing the end-user.