Never ask the barber if you need a haircut.

The line is a compact warning about conflicts of interest: people whose livelihood depends on a particular answer have a built-in incentive to give it. Asking a barber whether you need a haircut is analogous to asking a broker whether you should trade, a salesperson whether you should buy, or a pundit whether you should worry. In an investing frame, it urges independent judgment, skepticism toward self-interested advice, and the use of objective criteria (fees, incentives, track records, and alignment) before acting. The quote’s staying power comes from its humor and its general applicability to decision-making under asymmetric incentives.

["Never ask a barber if you need a haircut.", "Don’t ask the barber whether you need a haircut.", "Never ask the hairdresser if you need a haircut."]