never ask the barber if you need a haircut

== English == === Etymology === Attributed to Daniel S. Greenberg, who wrote “Don’t ask the barber whether you need a haircut” in the November 1972 issue of the Saturday Review, popularizing the saying. It was made more famous by Warren Buffet in his annual letter to Berkshire Hathaway shareholders. === Proverb === never ask the barber if you need a haircut Do not seek advice from a biased party.