The New York Times cites a recent study as showing that professors' ideology does not influence their students' ideology. If one actually goes to the original source, however, one learns, that the scope of the paper is exceedingly modest. What it shows is that taking an individual class from a random political science professor cannot be shown to influence the a student's ideology by the end of the semester.
Even assuming that the study is right (and I have some questions about its methodology that aren't worth going into), what does it prove? For one thing, as the authors themselves suggest, political science is generally considered a much less ideologically evangelical field than, say, ethnic studies, women's studies, English, sociology, anthropology, peace studies, Middle East studies, and so on.
More important, I've never heard anyone claim that they think that individual liberal professors serve as Svengalis who lure their students into liberalism by the force of their personalities over one semester. Rather, the charge is that if students go to college for four years getting primarily a one-sided ideological perspective, this will have several results: (a) they will be more likely to think that anyone on the other side must be a moron, since none of their smart professors seem to hold those views, and often disparage them, intentionally or unintentionally; (b) the "bias," such as it is, will likely show up in what is assigned and talked about, rather than explicitly in classroom discussion. So students will get a lot of Rousseau and Fanon, little Adam Smith and Friedman. This means that students get exposed to the "best" thinkers on the left, but rarely to market-oriented or conservative thinkers, which both reinforces (a), and also gets reflected in how people who go into relevant professions such as journalism, foundation work, and whatnot go about their business, even if their underlying political views haven't change; and (c)the implicit hostility non-liberal students perceive in the academy discourages them from pursuing academic careers, which makes the left-wing dominance of the academy self-reinforcing.
A personal anecdote that may be relevant. Senior year of college, I took a political economy class from a very left-wing, but very fair-minded, Sociology professor. One of the books he assigned was David Stockman's The Triumph of Politics. Stockman was a libertarian Republican who served as Reagan's first budget director. At the beginning of the book, he provided a concise summary of why he thought limited government was beneficial to the American people. When the class discussed the book, one of my fellow seniors exclaimed, "This was very interesting to me! He seems like a good guy... I didn't know that any conservatives actually cared about people!." Kudos to this professor for enlightening my classmate, but how does someone get to her senior year of college without being exposed to the radical idea that not all conservatives are innately evil?
Anyway, I don't know whether, and to what extent, professors' ideology influences their students. But I don't think that this particular study tells us very much.