No! Those you are talking about would not be the most qualified and your examples are a bit out of the common line. Martin Wolff, a failed lawyer, is a good case in point. In the US, he was convicted of felony, was banned and could not work as a lawyer anymore. He went to China and founded "holistic English", which means mainly showing movies to learn English. A lawyer who is not a professional in education nor in English and ESL now sells himself off as the grand man of ESL teaching in China. If that was true, we could close down all teacher training colleges and all Departments of English at uni. And this will never happen...hahahaha

In brief, someone calling himself a "teacher" in ESL and who cannot explain the difference between interesting and interested, for example ( a common mistake/error made by Chinese students of English), is not a real teacher and just a deecher (= pretend teacher). There is so much pretence in the ESL business industry, and a pretend teacher forms part of that muppet show.

Last not least, to explain the difference between interested and interesting requires at least two kinds of competencies: (i) You must know something about language and (ii) about pedagogy, that is, knowing how to explain it.

Mere Oral teachers of English who can't do that due to their educational requirements largely lacking are most typically the kind of white monkeys we find acting in the muppet show of crappy training centres.

The most qualified would be (for example) someone who's been on radio, does audiobooks, public speaking or actually a stand-up comedian would be among the most perfectly qualified. The problem is that a lot of failed young men who have teaching degrees in the west go to China for jobs and desperately try and pretend they are 'Qualified' and find people who are 'less qualified' because they are petty and insecure.