CFO is a starting point, not an answer — inspect the working-capital lines beneath it. FCF is CFO minus capex; FCF ex-SBC is the owner's view where equity comp is large; owner earnings strip out growth capex to show steady-state earning power. State which definition you used, every time.
A company with $500m of "free cash flow" that issues $450m of stock to staff has about $50m of owner cash flow and a rising share count. Persistent SBC above roughly 10–15% of revenue with buybacks that merely offset dilution means reported FCF overstates the economics by a wide margin — a workhorse of the short side precisely because it is fully disclosed and routinely ignored.
Receivables growing much faster than revenue, inventory outgrowing sales, payables stretching sharply, deferred revenue falling while reported revenue rises: each hides a different story under one CFO number. Capitalisation switches deserve special attention — moving costs from opex to the balance sheet raises reported EBIT and CFO at once while FCF is unchanged.
Educational, not investment advice.