generalising is not going to help anyone,Rottweileers,Dobermans and Staffordshire bull terriers are actually fantastic dogs
unfortunataly they tend to attract a mentally deficient level of owner who want a "big,bad dog" to validate their existence and they train them to be aggresive.these dogs then carry out actions in which they have been programmed,even if it is targetted at the wrong people......in 99% of these cases its the owner who is dangerous,not the dog