One of the reasons so many dogs get dumped at shelters - the people had no idea the kind of dog they were getting, what its needs were, the proper way to raise and train itโฆ
If a dog (as an example) flies into the U.K., they get quarantined for 6 months at the owners expense before they can be released into general population. And thatโs with current health conditions certification.
An ethical breeder should screen you and get you enough to offer you the tips, tricks, advice, or other resources (books, training classes) that they feel will be necessary for you and the pup to have the best shot at working out well together.
A good quality/ethical breeder might be a person you ask lots of questions before you buy a puppy from them but a good ethical quality/breeder will in turn ask you* several questions to make sure you are capable and wanting to care for the puppy properly.