What they mean by "muscle" breeds are the
Cane Corsos,Fila Brasilerio,Dogo Argentino and the Presa Canario.
These are all the new "rare" breeds that are around now.
They are bigger and stronger.And weigh up to 150lbs.
As for the good breeder making them bad.No.
Any licenced responsible breeder is not breeding them to be bad.It's the irresponsible ones that are making them bad.And for that reason only.It's the stupid people who want these dogs to be this way.They want the macho dog.They want it aggressive.That's why they are having them trained this way.
You breed a bad dog,10-1 you will get a bad dog.No matter how well trained you have it.Look at the woman who got the Rottie as a pup.She has tried everything.He was poorly bred by an aggressive male.
And I do believe that any breed can dangerous.Yes,even the small ones.No they don't do the damage of a large dog.But they still can.A dog can snap at anytime.And I don't mean as in bite.
"A dog can express more with his tail in minutes than his owner can express with his tongue in hours."