I've also had no problems with Ideal Hatchery and refunds when needed. I actually have found their chick-to-adult ratio to like actually surviving laying eggs much better than Cackles. Though I feel Cackles has some better looking birds for some breeds.
You just kinda get an eye for it over time. Looking at the comb growth and waddle buds. Almost aways, any comb ans waddle budding before 3 weeks is a rooster. Any red is caused from testosterone, indicative of a male. Breeds like old english game bantams and Japanese Bantams are incredibly easy...
Red Pyle OEGB, Partridge Cochin, White Laced Cornish Bantam from Ideal Poultry.
Rhode Island Red Bantam (terrible low hardiness, died before 1 year old due to internal egg issue, 2/2 of them), crele OEGB, Japanese Bantams (mottled), and Mille Fleur d'Uccle from Cackle Hatchery May 2022.