First of all, there is no "conspiracy" of Marxism and leftism on campuses. It's more of a general mindset, and a tendency to approve and hire like-minded people, and reject those who are not. The result is not a deliberate conspiracy, but an environment of constant leftist indoctrination, where the ideas heard in classes tend to always lean in that direction. Not because the professor is trying to turn out little Maoists, but because that is what he believes and that is what he teaches. Interestingly, the leftist tilt of journalism and the media works much the same way. Think peer pressure.

Unfortunately, the end results are not much different than if it actually were a deliberate conspiracy.

As long as there is no major dissension from the party line, you don't see much activity. But if you rile up the hive, like by inviting a controversial conservative speaker on campus, then you start to see how committed to "diversity" the university is.

If you can't find leftists on almost any large campus, you aren't looking very hard. Name a campus, and I could probably nail down a half-dozen radical leftist professors just from what I can find on line.