Yes, such interview and evaluation practices certainly beg the question about preferred credentials. In my opinion (others may have differing ideas) seeking teachers with advanced degrees is again, mostly a marketing tool, something the school can boast to student's parents when selling classes. I hold two masters degrees, which made it much easier to get hired, but did precious little to raise my salary above the standard rate. As I mentioned before, I feel that any success I had in getting a higher pay scale was due to popularity and demand for my classes by students, plus the fact that I had years of teaching experience prior to arriving in China -- not to mention the fact that I am American (a big plus in their eyes -- I think it rather silly).

Also when an applicant has a BA degree and higher, it is supposedly easier for the school to obtain an official "letter of invitation" from the government which then yields "foreign expert" status to the teacher.

The years I worked in training centers, an open class (all levels invited) called "Speaker's Corner" was offered to the students in addition to their smaller English classes (all centers I taught in would cap the class at 8-10 students). Many foreign teachers hate doing a few speaker's corner classes each week, but I loved them. If you can engage a larger group of people, discussing various topics, then all sorts of interesting comments, perspective, and discussion will emerge.

Also, it's another way for students who are unfamiliar with you, to experience your teaching style, and request your classes. I had to try lots of topics and methods to figure out what worked and what didn't; but once I knew what was usually successful in generating discussion (and fun), then I enjoyed them immensely. Again, the key is making students comfortable and building their confidence with English.