The first one I saw (wished I got this one!) was coming up to the front of the tank in the store, waving his claws around at my 2.5 y/o. My 2.5 y/o was having a ball, laughing, and the crab stayed out in the open the entire time. The one we bought later on hides all the time and we have only seen it a few times. I am disappointed that he isn't as "outgoing" as the first one I saw!
But I think crabs can have different "personalities" and you have to be somewhat careful with all of them to be sure that they don't get at your fish. The same thing applies to a lot of inverts, I understand. We had a coral banded shrimp for exactly 24 hours...he attacked and killed one of our fish so we took him back to the lfs
. Other people I have heard of have no problems with CBS. Luck of the draw, I guess.
husband has a 92 gal SW