It may surprise you to hear that not all flying schools are going bust but that many other businesses in other sectors go bust too. It's just that the nature of flying school cashflow is that going bust is much more likely because you can run on your cashflow and be bust without realising it for months and months.
It may also surprise you to hear that customers "expect" and frequently ask for a discount for payment up front, you have to give your customers what they want and if it's a discount they expect for an up front payment and they get annoyed if you don't offer the facility you'd be a total idiot not to take them up. The most that a flying school is trying to do is to get you locked in to a course of training if it's being badly run, then there are other markers but anyone who pays up front for ANYTHIING on a debit card or by cheque is the one taking the risk.
Most well run schools have quite a busy sim. They are expensive to run, yearly inspection, Quarterly Tests, independent quality manager, other post holders to be an FTO, sim engineer, bulbs (up to 500 quid a go) quite a lot of electricity not to mention the £150k plus to buy the thing and the cost of a guy to run it.
You can tell a she it school quite early on but you don't know how to recognise one until you compare it to a good school