MEXICO ESL HELP ?

Hello, I am thinking about going to Mexico to teach ESL (I would get certified through ITTO--a tefl program in Guadalajara) but when I asked on Dave's ESL cafe for some advice all I got were negative replies. They told me that since I am not certified to teach in the US then I will not be able to ever get a good job in Mexico and that the schedules are terrible, the pay sucks, the students are terrible, etc. (basically everything terrible which makes me not understand why they are doing it). I have lived in Mexico before and I KNOW that the cost of living is considerably lower than that of the US so obviously the pay is lower. I would just like to know if anyone on here has gone to get certified and teach ESL in Mexico (without being a teacher in their home country) and has actually enjoyed it.

I understand that my first year of working would probably not be the best job, but isn't it possible to move up with experience as in any other job?

Also, have any of you taught in either Monterrey or Guadalajara?

Thanks!