Tom is a merry fellow, that i'm pretty sure
Actually Tolkien did mention that he deliberately leave Tom Bombadil as an enigma. a lingering mystery. in fact, that's what make LOTR so interesting. he deliberately leave several blank spots of which he let the imagination of readers waging freely and his books become a topic of endless discussion.
A bit of topic: Did you know the "Fair Lady" that Tom mention when he took the treasures from the barrow?