The Extremely Fashionable trait is supposed to add "+1 trait bonus on Bluff, Diplomacy, and Intimidate checks. One of these skills (your choice) is a class skill for you."
I do not get the +1 to the skills, however. The skill I pick when adding the trait does become a class skill, and if I take a skill point in it I do get the +3 misc modifier. But the expected effect is for all three skills get +1 misc modifier, and when I take a rank in the one I designated class skill the misc modifier become +4.
This is the way it works with other skills that give similar bonuses (I tried Bully and World Traveller).
The bonus Extremely Fashionable conveys is in effect only when "wearing clothing and/or jewelry worth at least 150 gp". I added and equipped equipment costing a lot more, and still don't see the three +1 points.