I recommend that you visit your professors.
I recommend taking classes from visiting professors from other universities.
I'm not sure what you are asking.
"Visiting professors" is a category of teachers who are invited to teach temporarily at an institution.
If this is what you mean, then the first sentence indicates that the speaker does not have much confidence in these professors, as least as compared to regular faculty members.
If this is not your intention, gender is not indicated in the first sentence. Because of the gender reference, the numbered sentences suggest the potential danger of sexual harassment, which the first sentence does not.
To add to this, the place where the professor is being visited is not indicated. As a professor, both men and women students have frequently visited me in my office. However, relatively few have come to my home. (In those cases, I also knew most of them from outside of the classroom situation.) Since I often had night classes, students might come to my office at night, before or after the class session.
I agree with the recommenmdations of Ms. Sue.
I hope this helps a little more. If not, repost with more questions. Thanks for asking.
It has four meanings.
i. I cannot recommend professors, who are only visiting, highly enough. They're wonderful.
ii. I cannot recommend professors who are only visiting. They suck.
iii. I cannot recommend visiting one’s professor too highly. It’s wonderful.
iv. I cannot recommend visiting one’s professor. It sucks.