eventually it gets so bad that its shiny and sticky all the time - even in winter and in the shade. the rubber literally melts to a point where it changes its form and remains nasty. if a leaf or piece of hair lands on it, you can't wipe it off. literally feels as sticky as cheap duct tape all over, and is soft and tacky to the touch.
does that help explain it further? for the record, this car has been in the CA (and now AZ heat) its whole life, and seen plenty of sun - likely without a sunshade. Now that I own it, and after the new dash is installed I will always be using a sunshade when parking outside.