Well, in my experience, from raising a litter of st. poodles, and various litters of rescued rez dogs, it's pretty easy to tell them apart, if you spend enough time with them. You know which ones are male and female, they're all slightly different sizes, slightly different colours, and have personalities already... some are pushy, some noisy, some cuddly, etc. But alot of breeders do put ribbons or something on them so they're easily recognized, but a breeder that spends enough time with the litter, shouldn't need it