Im using a 1.4 tip on a gravity feed gun (non-hvlp), shotting a single stage 2k urethane. Compressor is out of the booth. I have a water trap after a copper tube that flows through a tub of water for cooling.
Im reasonably sure its not fish eyes, it basically looks like really really really fine sand has been applied all over and is trapped underneath, I did some very fine wet sanding after marking an area and they are definately tiny nibs.
However I can almost say 100% that its some type of paint problem rather than fine debris getting caught up in the paint, it is much to uniform and even to be dust.
At first i thought it may be the foam in the compressor air intake breaking up into tiny particles then flowing out through my airline, but ive changed setups and it still sometimes happens. Ive got a gut feeling it may be a humidity issue but am not really sure