Despite the fact that
University students can be really stupid I mostly agree with what
Noether has to say. I don't necessarily see them as contradictory.
I also do (I differ with West Country Guy) think that most students tell stories of their Lecturers' stupidity (hell, I tell people about my own stupidity ... see absent-minded for an example). I used to do it as an undergraduate, and I don't mind if students do it to me.
I still have respect for the good students, the people who actually try, who work hard in my subject, regardless of their marks. I have had some students who worked very hard and yet not got such good marks. These are the students you try to help, and you enjoy helping.
But an increasing proportion of the students do courses because they want to get a good job, not because they're at all interested in the subject. They put little effort into thinking about the subject, are mostly lazy and resort to copying and cheating to get through. I have no respect for these students; nor do I think they deserve my respect.
If students know little, it could very well be your fault. But if you've put your best effort in, and you've received objective feedback that you're an above average lecturer, then it can be and sometimes is the students' fault.