Linking verbs can be tough. There are the easy forms, such as "to be." These verbs link a subject to an adjective, which is why you say, "I am short" instead of "I am shortly." It's also why you say "I feel bad" instead of "I feel badly," unless you are, in fact, talking about your sense of touch.
But there are sometimes subtler cases.
For example, Joan Rivers got all pissy with someone on "Celebrity Apprentice" for saying, "I sat here and acted professional."
"Professionally," Rivers shot back.
Now, to SPOGG, to "act professionally" means to be paid for acting.
One way to see if "act" is a linking verb here is to swap in another adjective. I acted tired. I acted angry. Both of those sound somewhat awkward to us, but preferable to "I acted tiredly," or "I acted angrily." We'd say, "I acted as if I were tired." Actually, we'd be more likely to write that. We'd be more likely to say "I acted like a professional" or "I acted professional."
Therefore, we don't think Joan Rivers is right in issuing this correction. Nor are we a fan of all the plastic surgery, something that is entirely unrelated but must be said. Edit your language, friends, not your faces.