Good points here by everyone, so far.

I am working in Mexico (but hoping for a change very soon) at an institute with about 15 English teachers from different countries. Most of them are pretty good, a few are very good, but some are absolutely awful.

The hiring criteria at this institution are fairly strict compared to many places, but there are still teachers with MAs that are terrible, teachers with years of experience that are terrible and teachers with the minimum requirements (BA and 1 year experience) that are terrible.

To be a good teacher I think it is essential you understand three things, what your students want, what your boss wants and what you can do to satisfy their wants.

People insisting that students use X method because they just finished a thesis or a paper on that method are way out tune with everything. At the end of the day ESL/EFL is a business, and nobody would open a shop to sell their personal preferences while ignoring their customers tastes, would they?