How Do You Know If a School is Good or Bad?

If you are thinking of paying good money to study at a language school, how do you know if the place is any good?

I recently interviewed the owner of a new website that is going to monitor TEFL schools. 

It is still early yet so there are few posts but hopefully one day it will be a good resource for both teachers and students regarding which schools to avoid and which ones to consider.

http://www.teflspin.com/2008/03/tefl-news-teflguardian-to-monitor.html