Some businesses are highly complex whereas other businesses have a simple business model and very few employees. If you see your doctor for a personal health check they will start off with some standard tests and progress to more detailed tests if required. It is the same with businesses, there are significant similarities between most businesses so much so that standard health checks can be performed on almost any business. It is possible to run a business health check based on benchmarks from similar businesses. This however does not tell the business owner or manager if the business is going in the direction that they would like to pursue.
This will show your Angel Investor that you indeed are a rational thinker and concerned about the money as well as the truth. If the Angel Investor cannot trust you your chances of being funded are nil. An angel investor is betting on the jockey not only the horse. As an entrepreneur you must be honest with yourself as well as your financial partner. They want to make sure you believe in what you are doing and that you also have risked your own capital, time and energies into the new business. Angel investors want you to succeed and often they also like to give their input and if you end up taking their money for your startup, the need to realize that their input needs to be taken seriously.