That's an interesting question.
The refusal letter an applicant receives is a generic format letter, with some boxes ticked off saying, “We don't believe you're going to return home at the end of your visit.” They give you some generic reasons, which very seldom shed any light on what's actually at play.
To get the real reasons, you need to order a copy of the computer notes from the decision-maker to see what the actual rationale is.
May I say that those decisions are often very easy to challenge in Federal Court because they lack justification and transparency. It often seems that the officers have not properly reviewed all of the documentation, or maybe did it in a hurried manner. When they've listed the reasons, they've failed to really justify, with a logical analysis, why they've reached that conclusion.