I've recently coined this term as staring at the log and noticing inconsistencies in player actions (which number in the dozens, if not more) which results in suspicion. Which then used with a process of elimination mind set can prove to be very effective in finding the "thorns". I draw most of my "powers" from these kind of things. An example would be seeing who talks a lot Day 1. This usually means excitement which could mean the person has an interesting Evil role.