What's the difference between feeling nauseated and feeling detestable?

Solution 1:

"Nausea" is a very specific word: it's the unpleasant sensation that you feel when you may be about to vomit. To be nauseated is to have that particular unpleasant feeling.

I don't think "detestable" is actually a feeling. If someone said "I feel detestable", I wouldn't know what they meant. My two guesses would be that they mean either "I feel like other people detest me or ought to detest me", or "I have a detestable feeling—a horrible feeling that I detest".