It has been said that there is no such thing as a bad student, but merely a bad teacher. And while there are always going to be some students who are either too temperamental, too uninterested or too stupid to learn very effectively, these are the incredibly rare exceptions. For the most part, any kind of student is going to be able to learn reasonably well, if you give them the benefit of the doubt in that regard. After all, the kind of teacher that you are is going to be a major influence on the kind of student that they are.
Consider that your teaching style has a direct correlation to how well your students are going to learn anything. If you are abusive and vile toward your students, you may be able to enforce some semblance of submission. But when you are cruel to someone, you will only breed cruelty in them. After all, barbarism and tyranny will only breed more barbarism and rebellion in those under you. It is in the nature of all people to rebel against those whom they do not respect, and no one respects a coward who hides behind a title and the illusion of authority.
On the other hand, if you behave as if you have no spine whatsoever, and allow your students to do anything that they want, they are inevitably going to do everything that they want. That is, if they even show up for your class in the first place. After all, why would you go to a class and do whatever you please, when you could just stay and home and do precisely the same things, only with a little bit more privacy?