Eastern Indigos that are well fed and handled frequently are just slightly nervous when taken out of the cage. If not fed well, and hungry, just takeing them out can evoke a feeding response, as movement attract their attention as much as scent. This may mean that you COULD get bit. Usually, if the snake is hitting the glass in front of the cage when you go to take him out, he is hungry, which means that he could mistake your hand for his next meal, esp if their is ANY scent of any mammal on it. Cats included. I've tried it, it works
So, your best bet is to feed the snake well, give it adequate time to digest its meal, and then take the snake out, without hesitation and lot of fumbling around. Movement triggers their feeding behaviour,as does scent. So,use a snake hook if you must, but dont spend alot of time fumbling around the cage. These anlogies apply to Eastern(Couperi) and Blacktails. I have no idea about YT's, I have heard something about them and the devil, but it is probably just idle gossip. 
Best o' luck,
Fred Albury