The practical test set is short: does operating-cash-flow track net-income over several years, are accruals modest, is days-sales-outstanding stable, are non-gaap add-backs genuinely one-off, and do the footnotes reveal estimate changes that boosted profit?
Poor quality is not fraud. It is usually a series of defensible choices that each flatter the number slightly and together create a gap between reported profit and reality that eventually closes.
Example: Northwind Tools scores well on cash conversion and accruals but poorly on three points: a released bad-debt allowance, a payables stretch and restructuring add-backs in four straight years.
Related: accruals-ratio, cash-conversion, non-gaap, restatement, footnotes