Part of being a good reference librarian is being able to understand what patrons mean when they ask their questions. Often, the patron doesn't express their information need in a clear and concise manner... thus the need for a reference interview.
For example: A patron may ask, "What languages did the Vikings speak?" In his mind, he has communicated what he thinks is a clear information need. The librarian, however, can interpret his real information need to be, "How can I tell if I'm wearing too much cologne?"
The librarian's mission is now two-fold: a) find languages spoken by Vikings and b) let this guy know he is burning the hairs out of your nose. The first part is easy. The second may require some finesse. Be a good librarian and cough, gag, put your hand over your nose, or ask him to wait outside while you search for his answer. If he doesn't get the hint, light a match and see if he bursts into flames.