>Are these dogs unsuitable as pets (for non-farming households)?
Does the household have any toddlers to herd?
Working dogs that are not elderly to the point where they prefer to sit on their butts all day generally make terrible pets. Ones that are bred to herd animals and have been kicked out for biting them even more so.
I think it depends if you have the time and energy to exercise them. Kelpies, Border Collies and Australian Cattle Dogs are popular pets here in Australia, you just need to exercise them.
They are very intelligent, alert and loyal. We adopted a Cattle Dog and just had to be careful around toddlers due to herding, but otherwise he's very well adjusted.
He will follow you up the stairs and nip at your heels as you go, but he never bites hard and does it for attention/affection.