What do you think about teachers who give unequal treatment to some students?

I think it is unfair and cruel when a teacher does that for it might descourage some students and lower their grades, because the student need to be encouraged in order to keep improving and so the unequal treatment might damage his spirit and make him lose his enthusiasm. 

this is unacceptable-there should be fairness in teaching-

This is evidence of the lack of good qualification for the teacher Individual class teachers are responsible for managing their own students.
Each teacher should endeavor to resolve classroom management issues within their classroom.
At all ages, students are very sensitive to what they perceive as unequal treatment.
When students believe that their teacher favors some students over others, conflict grows in the classroom, and their trust in the teacher declines.
Every student has the right to be happy and safe while at school.
Students also have the right to be treated fairly and with dignity both in and out of the classroom.
While a student’s right to learn depends on the capacity of teachers to carry out their professional responsibilities in the classroom, both teachers and students have the right to operate in a school environment free from unsafe behaviour .

If that is done on purpose, then it means that that teacher has some issues that need to be addressed, or that he enjoys being unfair.
Some teachers do that because a student is weak and he needs more attention, or he is a hard working one who could not complete certain tasks for some pressing problems.

The teacher is the man who can make the learner should learn a Qader also said makes learner estranged from learning to differentiate between the educated is the exact indicator of the failure of the teacher Osa process management instruction

the Teacher need to be more Fair i think that the teacher should have HR Skills that Qualify him to work as teacher

Because teacher knows about the behavior and Psychology of the student and sense of understanding that is why Psychology is taught to teachers in B.Ed or M.Ed.
As being a teacher he must know and understand the Psychology of the student.

Teachers should always strive to treat each adult student with respectful equality, regardless of the student's ability or aptitude.

Those teachers should develop their love of the students.

The teacher's pet is never good - it is not fair to other students