I've found a good way to spot outlier people is to look for 'script-breaking' when you have a conversation with them. Because so many people are parroting things they've read or heard, most conversations fall into a handful of predictable scripts. You're mostly trading soundbites. Every once in a while you meet someone where you can't really predict what they'll say or how they'll think about something in a conversation. If they consistently surprise you, I've found that's a pretty good indicator that they're special on some dimension.