You can glean the interests of others and use that information to strengthen your rhetoric.
Benefit(s): When you use Diplomacy to change the attitude of a character, you can first attempt a Sense Motive check against that NPC to get a hunch to determine whether the character is under the influence of an enchantment, to use Sense Assumptions, or to determine biases for a verbal duel. If you succeed at the Sense Motive check, you gain a +2 bonus on the Diplomacy check, and if you learned any biases for a verbal duel, you learn one additional bias of your choice. You do not worsen an NPC’s attitude if you fail a Diplomacy check by 5 or more.
Pathfinder Roleplaying Game Ultimate Intrigue © 2016, Paizo Inc.; Authors: Jesse Benner, John Bennett, Logan Bonner, Robert Brookes, Jason Bulmahn, Ross Byers, Robert N. Emerson, Amanda Hamon Kunz, Steven Helt, Thurston Hillman, Tim Hitchcock, Mikko Kallio, Rob McCreary, Jason Nelson, Tom Phillips, Stephen Radney-MacFarland, Thomas M. Reid, Alexander Riggs, David N. Ross, David Schwartz, Mark Seifter, Linda Zayas-Palmer.