Ban that question
As we all know, search committees cannot ask job candidates certain questions. Questions about marital status, for example, or political affiliation. (As we also all know, some search committees will ask these questions anyway.) As it happens, Teller of Truths has an anecdote about corporate hiring that could be easily generalized to the academic job interview. When she asks her instructor why she needs to tell an imaginary employer "why we were dying to work for them," she is told that the truthful answer--"'Because one has bills to pay, including student loans, because you work a job you don't want to build hours for a job you do'"--is hardly going to get you employed. In other words, the desirable employee "loved the company with an almost cult-like worship."
Academic job applicants often find themselves confronted with the same question, and forced to come up with similarly insincere answers. "I have a passionate yearning to teach a five-five load at a campus located on the edge of a desert, with no local entertainment other than watching cacti grow." Since most interviewees have no real choice about whether or not to accept an offer, given the nature of academic employment--the usual "choice" being not between multiple offers, but between one offer and continued unemployment--asking them "why do you want to teach here" is, at best, a ludicrous query. (Anecdotal evidence suggests that it also reflects status anxiety; Harvard, Yale, and the University of Chicago are not likely to bother with this particular line of inquiry.) Moreover, the question also suggests that the applicants are the dominant agents in this transaction--why do you want to dally with us?--whereas most of them, if not just about all of them, are are no such thing.