Well I was never brilliant at maths, always in set 3 (bottom), and my teacher was actually pretty good. Then I worked in a special school where the maths teacher was simply brilliant. So it would seem as though the worst of us get the better teachers. However, I'm sure this isn't done deliberately.
But if people are having so much difficulty reading what the guy has written, then that's something that needs to be complained about, because it's jolly important in maths.
If other pupils/students feel the same as you, make a point between you of asking him to clarify everything you don't understand, and mention it casually to other teachers. As Lil ol lady says, you should really get your parents on board too.
Teachers, like human beings, can't be perfect, but they should at least make an effort to set an example to their pupils.