I've read about that very phenomena in Japan. Apparently it's fairly common for college and adult English students to take English classes for much of their school careers yet never actually achieve a basic level of fluency. They attributed it to a casual attitude towards the study of English as many of these same students were exceptionally talented elsewhere.
I have a somewhat tainted view of foreigners teaching English in East Asia; but I can see it being very frustrating for someone traveling halfway across the globe to teach and being met with very little interest from their students.