In my opinion, there is nothing wrong with a woman wearing a "dressy" tank top to a nice restaurant in Aruba. Indeed, you see many women wear them to the office in the summer (business casual look) and I think that many would agree that there is a difference between workout wear and what is being described in the posts in this thread. As for men and tank tops, I don't know of any/am not aware of any "dressy" tops that are made for men (they are mainly of the workout variety i.e. you would never see a man wear one to the office), hence, I would frown upon a man wearing a tank top in a nice restaurant.