A certain stigma surrounds the entire TEFL industry and those who become English language teachers. This less than pristine reputation exists for a number of reasons.
The main reason is the ease with which any native speaker can become a teacher and gain employment in numerous countries overseas. The great demand results in extremely low standards.
Quality of Teachers
This is directly related to the first point. Because the standards are so low for gaining admittance to the TEFL fraternity, many charlatans, frauds, layabouts and other riff-raff from the west enter the profession for the ease of lifestyle and possibilities for travel it provides.
There are few regulations that govern the industry in most countries and educational requirements for potential teachers are marginal. In some locations, a high school graduate can gain employment with few difficulties.
I like to use the construction industry analogy here. Years ago, after graduating from university, I worked at numerous different menial jobs before doing anything relevant to the degree I had completed. I worked for a number of years on building sites and discovered a simple truism that allows many unscrupulous bastards to prosper in countless different fields.
The greater the level of special knowledge required for the task in question compared to the relative ignorance of that same subject on the part of the recipient/customer, the easier it is to pull a scam.
Significant errors in the construction of houses are glossed over because the builders know the ability of the customer to detect such screw-ups is limited. This applies in other areas such as plumbing, car repairs and yes, even teaching English as a foreign language.
While knowledge of the English language is hardly equivalent to the technical expertise required in the other trades mentioned, the fact that most students are clueless as to what is right or wrong or whether the teacher in questions is an expert, allows many who lack the basic knowledge to continue teaching. The whole art/science of teaching is nebulous enough in its own right that this factor gets further exaggerated.
And the inability to gauge competence is further compounded by cultural confusion. Mannerisms, speech patterns and physical characteristics that expose drunks, wackos or other high risk individuals are hard to spot by those from different countries.
The TEFL Industry is a Racket
Yes, this is a huge generalization but it applies to a large segment of school owners and others profiting from the business of language teaching. They are in it simply for the money and don't give a damn about the quality of education being delivered. Many teachers and students who have been through the system recognize this and pass on the information to countless others and the reputation of all involved is further tarnished.
Regardless of how well a teacher was treated or how professional the school owners were, some people just get a kick out of maligning and belittling the whole profession. Of course, a negative opinion may be genuinely and strongly held. Just as some will rate hip hop music as a nuanced art form created by geniuses while others see it as tripe produced by thugs. Some class a filet mignon as a prime cut of meat cooked to perfection and some consider it a rotting piece of flesh heated up by an oaf in a white hat.
Negative views of the TEFL industry may prevail due to the fact that unprofessional circumstances and colleagues abound. And some of those feelings are probably because of self-doubt on the part of the individuals making the claims and as a way for them to explain away the fact that they never quite got their heads around any effective teaching methodology.
This psychology can best be explained by the famous Groucho Marx quote:
"I don't care to belong to a club that accepts people like me as members. "
People Who Will Never be EFL Teachers
Many people will never be EFL teachers, just as they will never be many other things. Their view of others who head overseas to teach in foreign countries is instructed by many of the previous points discussed. Everyone likes having certain paths in life that can be labeled and dismissed as it validates their own choices to a certain degree.
I'm not saying all those who have never taught English abroad hold a negative view of it. However, I have heard enough stories of those returning home and having trouble with potential employers giving little credibility to their experience to know that it's not considered the best career move by many people.
And that isn't a totally unfair assessment. Pulling up roots and heading off to teach half way around the world is a thought that never enters most people's minds. But the negatives act as a deterrence for at least some who might have pondered the possibility.
And that's not a bad thing as it keeps the numbers relatively small and the demand high for those who turn it into a life-long profession.