Hopefully I don't get flagged for piling on here ... but last night I reached into my baby leopard's enclosure and scooped him up before noticing he was deep in blue. His breeder warned me that he was very nippy, but over the last two months I've been gently working with him a couple times a week without seeing a strike.
Last night was no exception, he let me pick him up and explored around for a short couple of minutes before I put him back; not wanting to over stress the little guy.
Today is feeding day, and he popped out of his hide and struck the thawed rat instantly. He had no problem distinguishing food from friend.
Besides, there is no feeding tub training in the wild, and snakes have no problem telling what is food from what to fight, and what to hide/run from.