Yeah, Lionfish are in no way "dummies" lol. I can tell by the way my Dwarf Lion moves his eyes around that he knows exactly what is going on. I have never been stung, but have had my hand/arm in the tank quite a bit lately and my Lion doesnt seem threatened. He has really become accustomed to his new home, he has acclimated very fast. Hopefully he wont turn on me!
I have heard numerous time though that if you are one of those who is allergic to bee/hornet/wasp stings etc., the pain and discomfort is MUCH MUCH worse if you get stung by a Lionfish.