If it's going into restricted accounts like 401ks and HSAs you could be putting away a lot and still very literally be pay check to paycheck for your monthly expenses.
I think the term is widely enough understood that most people would understand it, but I also will agree that reliably measuring facts other than the fact of the popularity of opinion by a one-question survey that does nothing to confirm a common understanding of the question is very much unreliable.
This isn't a very good metric for determining financial health.