Dominance Aggression can be readily predicted by breed or breeds involved (cross breed) size sometimes and hormonal status .
As far as dogs understand we humans are part of the dog pack and that is why the aggression is usually directed to us and can be provoked when we alter the order of things in the dogs perception. For example if we demand unsolicited attention we get growled at. Or if we stand over him (even if it is just to put a blanket on him) the dog , being very aware of their personal space regards this as a trespass and will have no qualms at punishing you with aggression .Grooming , toweling , clipping nails and many other things that for the average normal civilised human been is perfectly acceptable , is not for the dominant dog while he is in that state of mind and it is our responsibility to help the dog to achieve a calm submissive state of mind so they can have a more fulfilling life in harmony with the owners.
There are dominant dogs that were born and "engineered genetically" that way. Humans can programme a dog to be dominant by the way we raise him....... we call that learned behaviour .If out of kindness and good intenntion we reserve the best couch in the living room for the dog's enjoyment (because he likes it) and we move to another place just to please him we are conditioning him to think that he deserves that treatment.I once had client who , when the whole family was gathered to watch TV, the pet would come to the father of the family and stare at him until he got out of "his" (ie the dog's)place in the couch .When I qusetioned the situation the owner very sincerely answered that he didn't mind sitting on the carpet . So remember that we are responsible for every stimulus that surrounds and influence our dog's behaviour.