Phil from Ajarn.com has commented about the number of letters he receives that are indecipherable. As Ajarn is a dedicated teacher's site one can only assume that these letters are sent in by existing or prospective teachers in Thailand. Speaks volumes for the literacy of some candidates.
We get applications from prospective teachers all the time, often accompanied by obviously fake degrees. (The most amusing example had the word "Registrar" spelled as "register" on the alleged degree certificate.) Basic spelling mistakes and horrendous grammatical errors give them away every time. Even International schools commit howlers. A position for a "Librarian" was advertised as "liberian" leading me to wonder whether the vacancy required a native of West Africa. Is it any wonder that Thais can't write a basic English sentence yet alone a paragraph when their foreign teachers can't either?