When I worked for HSBC, in order to supply a loan to anybody, we needed to do an affordability chart and present it to the manager. If the customer said she was getting a job with better pay, the bank should have suspended the application once it was accepted and waited for her to turn up with a contract of employment.
I suppose it depends on which bank you go to, there are a lot of people out there just trying to hit targets and earn bonuses not giving a damn about people.