If I were doing skill versus skill for social skills, I'd have the "target" defend with the same social skill being used to try to influence him. When you know all the moves yourself, you can more easily spot when you are being played. Although in some cases, the skill contest would be between two individuals who are both active, in order to see which sways the audience. A public speaking contest of skills to see which speaker wins over the crowd, a test of diplomacy to see which ambassador sways the King of Gildenvesse to support his nation in their dispute, or a seduction contest between two adventurers to see who woos the willing, winsome barmaid's company would all be skill-against-skill even if one didn't adopt that as one's standard model.