A Rottweiler dog would be a valuable addition to any family. They are loyal and brave and be both a protector and a companion. However, some often tag them as stubborn and aggressive. Instead of saying that, it would be right to say that they are fiercely loyal to their family and they guard them very strongly. The trick is to make them realize that who are the friends of the family he is with and that the rest are strangers.
It is easier for the Rottweiler pups to get accustomed to a new environment. They spend a very little time in the shelter homes or breeder houses to get close to the people who care for them there. They are mostly with the mothers and after they are weaned away from her and handed to a new family, it is easy for them to get used to them. The flip side to it is that the breeders do not themselves get a chance to know the temperament of the pup. Of course, they will definitely have a good overview about the kind of puppy it is from the way it interacts with the other pups but just like humans, their disposition might change and he much be a wholly different kind of a dog when he grows up.
However, in case of adult dogs, this might be little different. They get a lot of time to spend in the breeder homes and the breeders themselves are in a good position to know about their behavior. So if a owner is looking for a dog with a particular kind of temperament, it becomes easier for them to provide them with one such. But by the time the dog grows up, he becomes used to staying in a particular kind of environment and when he shifts to a new place, he might take longer to acclimatize. It should be remembered that he should be given the same kind of love and affection like a child- it would be wrong to leave him on his own thinking he is only a dog and will find his way.
The right way is to spend as much time as possible with the pup or with the adult dog initially so that he knows that these people care for him. That will make them more receptive to the other people when they come in. And also distinguish friend from foe, they need your guidance and this is only attained by good positive interaction with family.