So is this the same as Kidcastle Xian? it must be, surely.
Anyway, although I'm sure every teacher would have a bad experience there based on their reviews, I think that many schools are good, but only for certain types of teachers.
I suggest something along the lines of the following;
-What do you look for in a foreign teacher? (Once a school said 'a passport' which was refreshingly honest and informative.).
-If there are two days off, are they consecutive?
-(Question for the current FT) Are the other teachers friendly?
Will I have to do office hours or marketing activities, and of so, what exactly do you mean by these terms?
-How many foreign teachers are there?
-How close is the school / accommodation to the city centre? (especially with universities)
-What qualifications do the other foreign teachers have? (Might reveal their knowledge of teaching qualifications).
-What's more important; being a good teacher or keeping the students / parents happy? (A bit of an unfair question of course. If they say being a good teacher, they're probably lying).
-Describe the students. (I think that the best thing about my university is that the students are lovely, largely because they often come from the countryside and aren't spoilt brats, but I think that any answer here could be illuminating).
Generally I think that it's sometimes good to ask incredibly open questions, and see what people say. When I worked in the UK, I would sometimes ask potential customers, 'How are things?' and see what they said. If you asked a potential employer (or even current FT) that question, you'd probably be surprised what they'd tell you, because they can hardly point out that it's a stupid question. The important thing isn't your questions, it's their answers, and the more you can get a school to say, the more they're going to reveal about themselves.
One more thing, if you know something bad about the school, based on reviews or other people's experience, don't lead off with it. Perhaps beggers can't be choosers, or you think that things might have changed. It's ok to consider schools that have bad stuff about them on the internet, but give the employer the opportunity to address these kinds of issues without any prompting from you. You can gauge their honesty from the extent they acknowledge potential or historical issues.
You can also gauge their irrational paranoias for things like proselytising Christians or bad experiences they've had with FTs in the past. Again, let them shape the agenda for your discussion as much as possible, and just listen carefully to what they say. Hope this makes sense.
I'm chuckling away to myself remembering gaffes that various employers and contractors have said to me in the past, although I'm also aware of the times when I just didn't listen properly and paid the price.