Old Guo has been teaching for many years, worldly and smooth, he's seen plenty of rebellious students, yet many of those disobedient in school later become big bosses in society, often donating the most during school celebrations.
If a teacher faces difficulties, like falling seriously ill, these people are very generous, visiting and stuffing money without a word.
So Old Guo doesn't look down on such students; he realizes that rebels aren't rebels for life. Once they're in society, they naturally mature, respecting teachers like other students. That's why he never discriminates against any problematic student he's taught, making him quite possibly the most popular homeroom teacher at Second High.
Some troublesome students become bosses and frequently invite him to meals and drinks, or occasionally visit with gifts.
