"See this is the thing in China, if you're white you're famous." - Eddie Huang
TEFL/TESOL courses are preferred by some schools, however there is a list of other preferences (that are typically discriminatory) that will often outweigh TEFL/TESOL/CELTA qualifications. Do all schools in China, Taiwan, Korea, and Japan operate like this? No, not all, some schools will value qualifications and experience more, however they are not the majority.
Although it may seem harmless, this discrimination starts from the moment you send your picture along with your resume.
So what are these other preferences for?
Many schools prefer younger teachers. Often less than 30 years old. If you're over thirty or forty+, then yes you can still get a job, however you could be up against younger competition.
Here's an example of age discrimination in Korea.
"Female English Teacher needed in Kindergarten - Aichi, Nagoya, Japan"
Schools sometimes openly advertise that they are seeking a female teacher (more common) or even a male teacher (less common).
If you're attractive then you should have no problems. A clean cut appearance is the preferred one, without visible tattoos.
"Sorry they just told me that they want a white teacher." - some recruiter in Korea
Schools sometimes openly advertise (or sometimes not) that they are seeking Caucasian teachers. For example, I once called about a part-time teaching job and I was personally asked what the color of my skin was.
There was an ad placed by Giraffe language schols in taiwan called: English Teachers Wanted - Must Look Western.
Do you still have a chance if you're not Caucasian? Of course, it depends on the school. However, you may be up against Caucasian competition.
This one is less common, however I have seen a number of schools in Korea advertise that they are looking for "Christian" teachers.
Many schools prefer teachers from the States or Canada. That is usually the preferred accent. Here is an article on how an Irish woman and African American man were discriminated against in Korea.
This is a list of potential ESL employer preferences that you may encounter while teaching English in Asia. All schools do not operate this way, however many do. It goes to show that qualifications, will not always give you the upper hand over the competition.
From a positive point of view, if you ever feel discriminated against because of any of these reasons, well it shouldn't be a loss as they are probably not schools that you would want to teach English at anyways.
Read more about the ESL job hiring procedure (it's a comic).
See the interview above starting around 5:58. A Filipino American teacher talks a bit about his experience with racism in China.