Thank you to all who commented. I think the main problem is, when I have classes taught by actual professors, I'm more likely to fail. When I have classes taught by graduate students, I'm more likely to pass. That's a problem because graduate students teach mostly gen. ed's.
Professors:
1) are much, much more vague than graduate students,
2) don't write their main ideas on the board or type them in powerpoint nearly as much as graduate students,
3) are unlikely to create study guides for tests, whereas graduate students often do, and
4) require students to do much, much more textbook reading and whatnot outside of class than graduate students require.