1. A method comprising: classifying each of one or more terms, of a first text string, as a bad term, wherein a term is classified as a bad term if a search that was performed using the term yielded no search results, adding the one or more terms to a first list that is empty before the one or more terms are classified as bad terms; performing a first search based on the first text string; based on the first search, identifying one or more search results; after identifying the one or more search results, causing the one or more search results to be displayed; while the one or more search results are displayed, receiving first input that changes the first text string to a second text string; determining whether a term in the second text string begins with a term in the first list; in response to determining that a particular term in the second text string begins with a term in the first list, removing the particular term from the second text string.