Wow, i just learned something. For some reason I had always thought it meant associated attribute. Now I feel like the class dunce.
One thing to keep in mind with social skills, is that you can never have more positive bonuses than your natural attribute + skill rating. There is an optional rule that applies this to everything, but it is the default for social skills. So if you have no intimidation and a charisma of one (just using it as an example) you can't have more than a +1 bonus for being super scary to your intimidation.
Charisma isn't just appearance, it's your general ability to manipulate and deal with people. Ugly people can have high charisma.\
Also, social skills are used to resist social skills, so having some ranks in them is a good thing. Some GM's may let you use composure/judge intentions to get out of conning and intimidation, but it's an individual thing.