Not to get into the specifics of posters... My breeder DOES like to breed for smaller yorkies. Her target is a 3-4 pound Yorkie. She refuses to breed a female that is smaller than 5 lbs. She only breeds them with males that are smaller, since, obviously, if they take after their dad, and he's larger, it can cause problems for mama!
I had to explain that to a girl in my apt building who has a 3lb female and is looking for a mate. I tried to explain to her that it would be very dangerous, especially for a new breeder with no experience and no support... I mean, I wouldn't breed a dog without having someone like a mentor to help me through it AS WELL as my vet of choice.... Anyway, all that aside...
That's what my breeder says. Even though she tries for small ones, she definitely uses 5-6 lb females and hopes for the best... She tries to breed for personality after that. So size (male that will be a good match) and then she tries to "breed out" things like timidity, or stubbornness (hey, as much as you can! haha). At least, that's what I could tell, and I've spent a lot of time with her.
Also, don't leave! Even though I've just come back from a long hiatus, I can say that everyone here is here for the same reason- we love our pups... And the internet is the internet! Sometimes we say things on a keyboard that we'd never say face to face. You gotta check yourself when you're being rude and hope others do the same.