If you set a style that doesn't exist on a component, it is, basically, ignored by the compiler and ignored by the component at runtime. Call this:
myComponent.setStyle('MyMadeUpStyle','someValue');
Which will in turn call the styleChanged method inside the component, which will compare "MyMadeUpStyle" to the styles it knows how tohandle. If the style is not found, it calls super and is done with it. Most likely super will do nothing too.
I beleive styles were set up like this--as opposed to like properties--for convenience. Adobe didn't want to "bloat" components with dozens--if not hundreds--of extra get / set methods to support object.property notation for styles.