Aside from assigning points to Scoutcraft, you can get Lona physically dirty.
Usually, I just put her in the dirty rags set you can farm off skeletons and wander around 'til her dirtiness reaches max.
Edit: SCU is a separate stat that can be seen in the equip menu along with Sexy and Weak that goes up and down depending on what you wear and your condition. if we're talking skills, I'm pretty sure you need to dump points into Scoutcraft until the skill you want unlocks.