Effects of Leftist Indoctrination in High Schools
One effect of leftist high-school teachers (earlier discussed here) is that non-leftist ideas learned in college will be heard as leftist. For example, if a historian mentions that 18th-century revolutions were based on classical liberalism, it will be heard as a claim that Ho Chi Minh and Che Guevara were the equivalent of Samuel Adams or Patrick Henry.
Another effect is that students learning inane ideas from each other will think of those ideas as intellectual even if they didn't learn them in a college classroom.
Yet another effect is on people who reject leftist nonsense. Perfectly sound ideas (Darwin's theory explaining the fact of evolution, that open borders were the policy during much of American history, or that there is some evidence of anthropogenic global warming) will be heard as leftist and rejected. This in turn might convince otherwise apolitical scholars to turn left.