Keep in mind also, that oxidation state in organic chemistry (covalent bonds) is a relative term. For example, if you treat acetic acid with sulfur tetrafluoride, you should produce 1,1,1-trifluoroethane. By the above counting method, both acetic acid and 1,1,1-trifluoroethane have the same oxidation state. However, the electronegativity difference between carbon and fluorine is greater than the electronegativity difference between carbon and oxygen. The electron density around carbon has been reduced, which is the definition of oxidation.
Long story short, oxidation measured by whole numbers is merely an approximation.