all this being said, the worst dog I ever was around was an unusually large pointer bird dog. he got up out of the back of the p/u camper , stretched his legs, and jumped on my dad (riding in the front of home made camper), went completely nuts. he would come and go like that. won`t tell you what happened to him ! I had a big Rottweiler, wasn`t tied up, roamed a 1 acre yard. he was a great watch dog, if he didn`t like you, you ain`t coming in my yard. if he liked you, come on in . think he could tell a persons intentions or demeanor or something. clean up helpers from louisianna up here for ice storm clean up a few yrs back, he wanted to get to them thru the 6 ft chain link fence, next day an insurance adjuster came out to survey the damage, dog let him walk right in. go figure!