I learned the hard way what overconfidence gets you when handling a more aggressive snake will get ya... bit!
Last night I was handling a Emerald Green Tree Boa that I was thinking of getting for my collection. He/She was not showing a lake of comfort with me, meaning no hissing, wagging of the end of the tail or any visible sign of aggression. I had a good grip of the back of its head for safety and held the snake for a good 5-10 minutes.
I went to put it back in the cage and made the mistake to take my hand off the back of its head and BAM! Took a lot of work to get it un-clamped from my hand. Though I will agree, getting bit dosnt hurt much, more like a over blown paper cut but I did learn not to read to much into body language and treat it as if it will bite no matter what.