We have had an aft balcony twice, most recently on Caribbean Princess. We didn't notice any diesel or vortices. You won't feel much air movement at all. Our neighbor smoked an occasional e-cigarette. Can't remember, I think Princess may have banned smoking on balconies.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016
Sail Windjammer: Mandalay 2017
Star Clippers: Royal Clipper 2015