It is what we call a "rhetorical question," which is a question that is really used to make a statement. I really means "I think Karen Marsh looks old! Do you agree?" It is the type of question you would only ask when Karen Marsh could not overhear it. It is called "gossip."

It means that she looks old. This sentence is more like an exclamation to emphasize a statement or idea. It's a bit easier to tell in voice than by reading. It is a rhetorical question since it is trying to make a point instead of seeking a real answer. (Granted, you can disagree, and say that she looks young but it would probably catch the speaker off guard, since they would not be expecting a negative answer.)