A tutor so fixated on their way of doing things that alternate approaches/partial solutions are considered wrong and the student is steered towards the tutors method.
Even if a students solution/proof is incomplete, the tutor absolutely owes it to the student to give an answer as to whether or not that method would have worked, and its pros/cons vs other methods. Stifling creativity in math is very very bad.
Most tutors could probably learn a thing or two from their students methods too! Even it is something like "this is why approach X to class Y of problems is not taught as the standard way".
Same goes for tutors who dogmatically stick to a set way of explaining a concept that a student is struggling with, repeating the same thing over and over and getting frustrated etc. Most concepts can be described in pretty different ways, and different students will have different ways of naturally understanding abstract concepts. Being a good tutor/teacher is about understand the material well enough that you can approach it from many different viewpoints, rather than just one. (This is important to being good at math in general, but you can get away without this level of understanding in high school.)