The answer to that question highly depends on where you are buying the chicks from. Hatcheries tend to get their chick's sex right with the exception of Hoover's Hatchery, which is where Tractor Supply gets their chicks from. I have learned that typically in every "sexed pullet" bin at Tractor Supply, there will be at least one cockerel there, if not a few more.
To the trained eye, sexing chickens is easy. The average person can sex their chicks at six weeks, which is when they begin to lose their down feathers and replace those with normal plumage, making them look scraggly. During this time, you can see whether their feathers are pointed like a cockerel's or rounded like a pullet's. Sometimes, though, sexing chicks can come far earlier than that. My Cochin Bantam cockerel had large reddening comb and wattles, and he started crowing at about three weeks old. I have heard cockerels begin crowing as early as two weeks old, though that is rare.
I was starting to believe their "pullet" bins were really straight run bins.
It really does seem like that, and the lack of employee knowledge is incredibly widespread. A year ago when I was getting four bantam chicks, we asked a worker there what breed they were (even though I could already spot out multiple breeds myself). They said they were bantams. We told them that bantam is not a breed, it is a size class. Then they said that the breed must be Unsexed or Straight Run since the sign says so.
And yes, I tend to always come home with a cockerel from the pullet bin but for us it's better than 9 out of 32 straight run pullets lol
