Having raised toy poodles for 12 year years, that has not been our experience whatsoever. The toy poodles were we raised seemed crème de la crème in intellenge. Of course owners were a different breed.
I used to breed and show Siamese cats, and I bred first for temperament, next for health, and only last for conformation. Had one champion, just the same.
Lots of folks weren't that picky and bred just for looks. There were plenty of mean, sickly Siamese around.