Thanks for the article.
I don't try to correct students when they pronounce the "f" sound as "p" as in "beautiful = beautipul" or "v" as "b", but I notice that some co-teachers may interrupt and try to correct students. Other co-teachers interrupt and explain or pronounce words incorrectly.
As for classroom behavior, I wish someone would acknowledge and give advice to teachers who work at vocational high schools. The general idea conveyed by many articles is that students are diligent and want to do well in order to get into a good university. That is not the case for vocational high schools. I think these students have the idea that the system has given up on them and pushed them out of the 'normal' curriculum, so why should they bother to pay attention in class?