Thanks for your reply! It's quite difficult to find a teaching position which is not advertised by one of these agencies and, after some research, I've found out that schools usually hire teachers through recruitment agencies. So the question is, which agencies are reliable??

I'm specialised in teaching Spanish as a second language, and this agency wanted to hire me to teach English despite I'm not a native speaker - that made me suspicious amongst other things.

I'd like to avoid agencies. It's hard to find ads not published by these snakes, though. I don't know where to look for a 'serious' teaching position without being treated as cattle...