all monitors have the ability to be relly mean. i cant think of a single peacefull monitor. in the wild they are visious hunters. with that said. there are different types that seem to tame down more than others.

akies
black throats
savs
and a couple others.

when i bought my sav i must of looked at 5 diffent stores till i found one that didnt mind being held to much. and we took him home and built on that. black throats are like most lizzards or any herp for that matter they are born with a internal trigger to be scared and flee or attack anything bigger than they are. so as they get bigger and begin to trust you they usually calm down verry nice. my sav is awesome. ( as long as he is not hungery. if he is hungery he will bite anything that comes in his cage but if he is well fed you can reach right in and pick him up.)