YEah, jackson's do that, they'll ram you with their mouth open, but not clamp down...not the case with veilds...I had one of my old bloodline on my shoulder, my friend scared it, and it bit the back of my head--drawing blood--through my (very thick) hair. I know of several people that have had their thumbnails split from veilds. A dealer I met at a tampa show had a big mean, WC veild when they were first imported. The guy had the tip of his finger bitten off the bone.
I got bit by my first deremensis when he was a few months old, very strong bite. That was the only time a deremensis evert tried to bite me...it's hard enough to get them to gape at me...they're usually very mellow.
My friend ticked off a big male parsonii years back--scared the heck out of him. It just turned, looked at him, opened his mouth, and let out this loud, slow, deep hiss--like the queen alien when she see's sigourney weaver the first time in Aliens...
Almost got him too.
My veild hasn't bitten me yet, and it's not for a lack of trying. He's big enough to break a fingernail. Chameleons probably have the strongest jaws of any lizard for their size--they're just about the only lizards that chew their food.