my silky and second yorkshire were from petshop but they are both healthy n with good temperament.
My first yorkshire was from breeder but he was sick when he was a pup-runny nose n cough.His temperament is not very good. He is only sweet towards us and his two pals.
Other than that, he is very defensive and not friendly with humans and dogs.
Getting into fights is common for him. But we still love thaty head strong guy to bits.
He is big for a yorkshire as well -around 7pounds.
So, in my opinion, not all petshops are bad.