>You've done a man's job, sir
A person of average or higher intelligence realizes that Gaff's line is ironic. Deckard's job is dehumanizing and has left him traumatized and emotionally void. It's the least subtle cherry top on top of the movie's themes, that Deckard has made himself inhuman and now learned humanity again from the Replicants' struggle to live.

A retarded person hears that line and thinks "OH SHOOT what if this means DECKARD is a replicant too???" Ridley Scot is a retarded person.