Just to keep it informative, there's a slight layer of grease on the ball, just not enough to allow dust and dirt to adhere. They're not as dry as it appears. And they've survived the ODOT winter ice treatments, which have proved to me very corrosive to many vehicles.
Edit: If you look...
Might want to consider these TG wipers and seals. I've been using them for the last 5 yrs and here's a pic of my DS knuckle currently. No leakage or residue of expelled grease on axle, knuckle, dust shield or steering arms.
I'm sure there'll be comments that it looks dry. But there is no need...