As a small government guy, I can say that there is a huge liberal bias in college where many leftist Professors regularly shoved their political views on to the class. I think there is room for having great political discussions where the Professor plays Devil's Advocate and throws out ideas to challenge all people's views and push people outside their comfort zone, but that is never how these professor's operated. It was always a mocking of the right, a straight up proclamation of liberal views as superior or a challenge to anyone who disagreed with the teacher's views. Occasionally, I or someone else would debate with a professor, but it's very difficult to debate on a random subject that the Professor knew was coming and you didn't. It's also difficult because the Professor has built in credibility, so it's an uphill battle all the way. If you don't have an instant answer for every question which a professor thought of in advance. Then you look stupid.
, but the culture is very biased, and it's a shame because it really does hurt those who aren't challenged to think outside the box. If professors would challenge all ideas, I'd have massive respect for them, but when teachers only spout off ideas from one side of the political spectrum and tries to take apart ideas on the other side, it's rather transparent that their goal is indoctrination.
Several times in my college, I have witnessed both liberal and non-liberal ideas get shut down; and I go to college in Manhattan (pretty liberal environment). You're overgeneralizing your experience with college faculty to all colleges across the country. Most professors are fair and professional (at least in my experience), but if you speak out of turn to bring up politics in class you better have damn good evidence as to why this rant is relevant to the lecture and why you stand by the allegation. It's not about persecuting students for their politics, it's about using critical thinking to separate fact from opinion.
Furthermore, empirical evidence isn't political brainwashing. Most leftist theories are well rooted in peer reviewed studies and have credible data to support them. Just because it's harder to prove trickle-down economics or harder to disprove links to man-made climate change doesn't mean that the colleges are going out of their way to support liberal ideology and undermine conservatism. Some viewpoints are just more compatible with the scientific method than others.