Every time we sail Carnival, I make it a point to trek up to the "Optional" deck to make sure the lovely Mrs. Jones isn't there! (that's my story, and I'm sticking to it!) Seriously, it isn't a very popular spot on most cruises, however occasionally it will fill up. No big deal, as most of the people there are the ones who you wish would have stayed in the cabin.
What happens on the topless deck, stays on the topless deck!
Have a great cruise,