When people write case studies, some list gross income and others list something similar to "Monthly Net Salary: (after taxes, insurance, etc)."
If all they want is for posters to say "stop spending a zillion dollars on cable and caffè latte", gross vs. net income is irrelevant.
But if they want comments on their overall cash flow, ignoring taxes and "etc" risks overlooking significant issues. Two examples: "incorrect withholding" and "opportunity for better use of pre-tax options".
Of course, people will do whatever they want. If case study writers merely overlook the benefits of examining the cash flows between gross and net, however, it could be helpful to guide them.
In How To: Write a "Case Study" Topic, there is currently no mention of gross vs. net income.
Question: What do you think of suggesting that people start with gross income when writing a case study?