Anything from Udemy with instructors who don't speak CLEARLY, and instructors who fail to provide solid code explanations (ex: they just type some shit and expect us to understand what it's doing, and they move onto the next topic).

Add instructors who pretty much copy a tutorial verbatim - they just go through someone else's tutorial (without referencing the authors' work) and claim it as their own.

I'm sure I have more to add, but I'll stop here. :P