OIly skin, not oily skin, washed hand, didn't wash hands. It really shouldn't matter.
At any rate my skin is very non-oily and when I got my 3rd controller I made sure to be the only one touching it ever. It's the Left Analog that degrades. Not the Right Analog stick. It took awhile, regular, good practice of playing using that controller, but it degraded on the Left Analog just like our first two DS4's that were used by the whole family.
Good practice of playing = play normal, wash hands before playing, don't eat and play at the same time. Don't use the Analog sticks wrong.
Wahsing hands: I don't use lotion or lotiony hand washing stuff. Water and soap, then rinse very well, dry off completely.
In the end all three controllers have the hard surface below the rubbery coating of the stick, showing. All three controllers came from one store. One in the PS4 box, one separate the same night, one from the shelf many weeks later.
It does seem to be a problem as many like you are reporting the same very condition.
Now, before you get another controller, & experience the same exact issue, spend $5 bucks on some "grip-it" stick covers & be done with the problem.
No matter what you do with your current controllers...send them in for warranty / exchange, whatever...get the covers so you won't have to deal with this annoying problem again.
As I said earlier, I was having no issues with both of my DS4's but I went ahead & got a pack of covers just to make sure I didn't.
It's worth the money to put the hassle behind you bro.
I have 2 controllers that had the rubber on left stick fall apart. It literally splits around the rim.
I sent 1 back to Sony and the replacement appears to have textured rubber on the sticks similar to my DS3's, the damaged one I have as a smooth textured rubber.This controller also had the R1 sticking (I do not eat while gaming so it's not due to grease or sticky drink) I will be sending the 2nd controller back for replacement this week.
It appears to me that there may have been different batches of controllers shipped and the less textured versions are suffering this problem, at least I hope this is the case because this is my only disappointment with PS4.
This is nothing to do with user! I still have 4 fully functioning DS3's that have only needed a clean out since 2007 and finger nails are short