I have met teachers with very low quality, lacking professional ethics, poor teaching ability, insulting words, disrespecting students and being treated unfairly. The words and deeds of these teachers may have a negative impact on students, and may even affect their growth and development. We should strive to improve the quality of teachers and provide a better educational environment for students.

Here are some common examples:

1. Insulting words and deeds: Some teachers may use insulting language or behavior to treat students, which may make students feel insulted or hurt.

2. Lack of respect: Some teachers may not respect students' opinions or ideas, and may even laugh at or belittle students' opinions.

3. Unfair treatment: Some teachers may be partial to some students and unfair to others. This may make students feel unfair and affect their enthusiasm for learning.

4. Lack of professional ethics: Some teachers may use students to seek personal interests, such as asking students to help with private affairs or asking their parents to provide benefits.

5. Insufficient teaching ability: Some teachers may have insufficient teaching ability and cannot effectively impart knowledge to students. This may cause students to encounter difficulties in their studies and affect their academic performance.