most likely hj your intimidating the skink or trying to hold onto it maybe stressing it. I like to think all animals/herps dont forget things. So best to be calm but in control at the same time letting them do what they do, and after a while they may end up with a bit of respect for you :lol:
blues seem to like to walk all over you, not so much be held still in your hand, they shouldnt hiss all that much really, can be agro things but generally laid back chaps. Is my understanding they hiss to wear of an intruder/threat or if they get a fright etc.
all 3 lizards are amazing, blue tongues i find easier care, i think the dragons are a lil more work but maybe more fascinating, could watch them chasing down and chomping back food all day