My car is almost two years old with over 20k miles and I have not had this problem at all. I am guessing that most of the people that are having this problem probably tend to leave their fingertips resting on the buttons even when not pressing them and the oils are causing the problem, just my $.02.
That wan't my experience.
The button problem was well known to me, so I avoided using / touching them, except as-required. Even then I only used the pad of my finger, not the nail.
They still failed.
My 2¢ ...