That's EXACTLY why he is so dangerous.
Adventurer Soon-Dead : "Hey guys we're pretty tired. Lets check out this little secluded side cave and try to get some rest."
Adventurer Gonnabiteit: " I don't know. We haven't really checked it out yet."
Adventurer Soon-Dead : " So what? I mean, how bad could it be? Its not like there is mega-powerful lich in there just chillin and waiting eat our souls the moment we walk in or anything."
Adventurer Gonnabiteit: " Heh. Yeah I guess you're right. Lets do this."