Some English teachers operate under the dubious philosophy that if they speak English poorly, their students with comprehension problems will have an easier time understanding. Sitting next to one of these teachers provides one with a steady stream of dropped articles ("a", "the", "an"), plurals that lost their s's, and adjectives subbing for adverbs. An example would be something like, "boy walk quick to store," instead of, "the boys walked quickly to the store." This sort of poor English speaking is only serving as a model of poor habits for the student and makes the teacher sound like a complete and total idiot. It does nothing to improve comprehension as few students are getting hung up on removed components of the sentence. Usually, their inability to understand is linked to vocabulary, listening only for keys words, or confusion about differences in Japanese and English grammar. It is not helpful to devolve into "me Tarzan, you Jane" grammatical patterns.
I cringe when I hear a teacher speaking in this way, and I hear it all too often. I think it reflects poorly on English teaching in Japan and underestimates the Japanese. I won't miss hearing people who think speaking like a caveman is somehow helping their students learn.