Gym socks are known to be smelly since they absorb sweat, so saying that the police department is like a pair of three-week-old gym socks implies that it is smelly and not clean
Consider the statement "The entire police department in Ashland is clean.". Is the statement "Face it, caine, the whole ashland police department is like a pair of three- week-old gym socks." false? Yes/no/unknown