PSA: There is a secret Accessory that boosts the efficency of scouting
I was looking around the Monsterpedia, particularly the Traits tab, and I noticed one was missing; searching for answers I learned that the Monsterpedia also enlists all the traits, including those exclusively given by accessories. Since the missing trait wasn't from a monster, I looked at the available accessories list on english sites but still nothing. Turn's out, they are incomplete (and even some japanese sites don't have the "complete" list)
Eventually I stumbled on a japanese site that enlighted me: There is a special, secret accessory, the Scout's badge, which grants the trait Scout's Honour. This accessory can only be found in a secret room in Conqueror's Keep (Randolfo's Castle) behind an illusory wall on the 5th floor, in the room beside the last room before the boss.
As you can guess, this accessory trait can increase the scouting success rate once equipped. Very useful for the more difficult monsters to recruit, expecially in the Mole Hole.
I will provide a image with the location, this is an information that needs to be preserved and spread :)
I slighty modified the original image with some extra info in english