Not always.
I handle mine almost every day, sometimes for upwards of 20 minutes, and that helps with taming - it teaches them that you aren't going to kill them.
I've been trying association training/taming by putting a waxie in my hand when I put it in the tank (instead of just grabbing them, which I only do if they need to be moved then and there) and when the leo climbs up to eat, you pull your hand out. In theory, they'll suddenly realize "oh, getting on the hand = food"