A person who is considered to be unreliable can still be right about something every once in a while, even if it is by accident.
Example: When I was having car trouble, a friend of mine, who knows next to nothing about cars, took a guess and said that the problem might be a belt on the car’s engine. After taking it to a repair shop, it turns out that my friend was correct, but even a broken clock is right twice a day.
This phrase is also said as ‘even a stopped clock is right twice a day.’ (The word ‘broken’ is sometimes substituted for the word ‘stopped.’)
Origin Of ‘Even a Broken Clock Is Right Twice a Day’
A broken clock is obviously going to be unreliable, as it cannot properly tell you the time. So whenever you look at it, the time it shows will be wrong. Well, mostly, because even a busted clock that has its minute and hour hands stuck in place will still be right twice a day, hence the clock is correct on occasion. This is comparable to a person who, like a broken clock (in that they often give wrong or unreliable information about things), even they can still be correct at times.
This phrase goes back to at least the early 18th century. It was used in a magazine called The Spectator, by Joseph Addison and Richard Steele, from the year 1711:
“If instead of running after the mode, they would continue fixed in one certain habit, the mode would come time or other overtake them, as a clock that stands still is sure to point right once in twelve hours.”
Note: Did you know that when it comes to the origins of phrases, there are some that are unknown? Indeed, and in cases where this happens, what I’ll usually do is one of two things:
If there are explanation(s) that exist that try to explain how the saying came to be, then these might be included on the page. Or if no explanation exists, then a quote will normally be included on the page. These citations are typically the oldest known form of the idiom in print.