Playground (and White House) Taunts
At least to someone my age (born in 1959 — you do the math), the expression “it takes one to know one” is inextricably linked to a playground taunt.
The usual exchange (typically between adolescents, the Trump administration notwithstanding):
Child #1: “You’re a doody head!”
Child #2: “No! YOU’RE a doody head!”
Child #1: “It takes one to know one!” (sometime followed with a “Nyah nyah nyah nyah nyah nyah“).
All of which is unfortunate.
Because, when it comes to fields where it’s hard for laymen to judge professional acumen (Realtors, electricians, and surgeons all come to mind), it really does take an expert to recognize another, highly skilled expert.
See also, “You Take the Cake!” (& Other Ruined Expressions)”; “Synonyms for “the check’s in the mail“; “Why is Calling Someone a ‘Piece of Work’ an Insult?”; “That Guy’s a Real Ottoman”; and “How to Tell if an Electrician ” or ANY Contractor ” Knows Their Stuff.”