Unfortunately, places selling female chicks have no way to verify the sexes and that hatcheries only "guarantee" 90% accuracy, some some of the alleged females will turn out to be males. The hatchery's guarantee is usually that they will refund the difference in price between the males and the females, not much money and not usually worth the hassle, which is what they are counting on. The whole system is designed to ensure profits for the hatcheries and they really don't care that some people can't deal with even 1 rooster. I make it clear about which chick and ducklings I can sex.
The only way to be sure (well, 99.99% sure) is to get breeds or hybrids that are sexable by color. Sexlink hybrids are perfect, as are any of the autosexing breeds, like Legbars, Welbars, Rhodebars, etc.
Hi Dennis, what kind of autosex/sexlink chickens will you have next spring? I definitely want
Cream Legbar, Welbar, Olive Egger, Blue Egg Black Sexlink/Pennsylvinia Black (most important one). Do you still have the Barred sexlink?