Here are ways most unethical breeders, BYB's, PM's, and brokers cut corners in their plans and the first one listed is why you get a lot of Yorkies that aren't standard and look a bit off (hair, ears, body, face, etc.) once they get older.
1. They cross breed a
female Silky with a
male Yorkie because she can produce a large litter and then call them Yorkies, because most gullible people don't know the difference.
2. They do no health testing...NONE...but lie and say they do because they have learned how to "business talk" to buyers to seem legit.
3. They sell the puppies at 6-8 weeks old to cut their own expenses to make
$$$. These puppies have not been wormed or had their first set of shots. 4. They claim they have a health guarantee 
again... this is "business talk" and doing #3 above is a big clue. 5. If you are lucky to go to their homes the mama dog usually may not even look like she has been nursing, or they may not have the neither of parents on site, or they may give some bogus excuse about them. But they miraculously have a litter of puppies (BROKER)
To all you puppy shoppers out there.... PLEASE do research and educate yourselves and not fall victim to puppy wanting fever. Have patience and find a real Yorkie from a reputable breeder.