I wanted to share with everyone the condition of my shocks after races and what all of you shoudl consider as routine maintenance.
I have found that after a couple of races (dry conditions) the internals of my shocks are somewhat dirty and the oil is not clear. Even with good seals, the shocks are drawing in dirt and contaminating the oil. Every time I have taken them apart, they have been dirty. But not too bad.
Recently, I raced for 2 hours in a muddy mess, running the rig hard. When I pulled into the pits after the race, one of my front shocks puked all over the ground. I decided to replace all of the seals inside the shocks on all 4 corners figuring if that one went, the others couldn't be far behind. After taking my shocks apart I was amazed at how nasty the oil and internals of the shock were. The oil was a VERY dark brown color and looked like thined out muddy oil. The spring inside, shims, and internals were all covered in that thined out muddy oil, all of which needed a thorough cleaning.
The moral of the story is that even if you are not racing, you should consider having the shocks serviced (insides cleaned and oil replaced). The interval of the service is going to be highly dependent on how hard you use your rig and how often. I use my rig about every other month and I work it hard for about 2 to 3 hours. You probably should look to have them serviced maybe once a year to insure they last a long time. It isn't hard to do, and would go a long way to longevity of the shocks. Rebuild kits are about $17 each.
Just food for thought...........
I have been running the FOX 2.0 air shox for 10 year on my Honda Pilot, I have taken them apart many times over the years and have never had dirt in my shocks, yes the shock oil is always discolored as it is in any other shock but never any solids or anything like you describe.
In your application is dirt being sprayed right on the shafts of the shocks? Cant tell get out a magnifying glass and look at the shaft on the shock all the way around I would think you could see micro scratching on the shaft if its being sprayed much.
You tried running a rubber boot over the shock, for about half my shocks life I ran them with just plain old automotive shock boots covering mine, fork boots off a motor cycle would be a better fit and probably look better
What oil are you using, I found the same results with oil discoloration in both the FOX 0W oil and Bel Ray 5W 10W and 15W oils.
My shocks have thousands and thousands of hard off road miles on them and I am still using the factory installed seals on all four shocks, I did have one shock leak once but it turns out it was because the top out spring broke and a shard of metal worked between the seal and shaft, I cleaned the seal and reused it, no leaks to this day, I do have 4 new shock rebuild kits just in case they leak sooner or later it has to happen.