This is "เลี้ยงไม่เชื่อง" which appears to mean "untamable" or "inability to civilize". Here is the sentence from a story:
"ความเหมือนอีกอย่างหนึ่งคือพวกมันทั้งหมดถูกตราหน้าว่าเลี้ยงไม่เชื่อง ฝึกหัดให้ดีไม่ได้"
"Another similarity is that all of them are stigmatized as being 'untrainable', no matter how much they practice." Or,
"Another similarity is that all of them are stigmatized as being 'untrainable'. They can try and try, but to no avail."
What do you think? Thanks.