Recently someone posted that their CV joint(s) were drying up and making noise. They asked , "{where does the grease go?

Well, a friend rode with me a couple weeks ago and said- you got a dry CV joint -it was making a hideous knocking sound. 

So, today, I removed the right rear axle and found the outer CV joint as he said- dry as a bone. 
The inner is still greasy. 
The outer is not looking good. I'll have to replace it.

Now I am asking the question- how does it dry up when countless old CV's I have looked at have are greasy after 20 years. 
 Is it the brand of grease?is it possible to put the CV joint backtoghter wrong?  I will admit I have only been rolling on CV's for seven of my 23 years of VW's. 

So - obviously i don't know everything and it is time for me to look at the maintenance interval chart and grease these things on time. I got a refund for my grease needle which was garbage and I knew it would not save me from this problem which I allowed to exist too long. 

Part of the reason for this is that the noise went away for a couple of months. I thought it was something else. 

Robert K

1982 Westfalia