yeah I don't know about this and what exactly causes it. When I pulled my intake to do my delete last year it was gooey as hell. Wasn't having any signs of cooler failure or egr problems. Logic however tells me that moisture in the carbon is bad
Maybe one out of every 10 valves I pull is all covered in that crap, the rest are just dry soot. It's really hard for me to say what causes it but I usually try and push for cooler replacement in that case. You wouldn't think CCV oil would be able to make it up to the valve since the constant exhaust pressure would force it away.
I had that gooey mess originally. Now I don't (dry powder all the time). Not trying to tell anybody what to do, but relating my experiences.
These are the things I did - who knows which one(s) resolved it:
1. Reflashed to latest Ford program (changes the EGR operation until truck is warmed up, cycles the turbo, etc)
2. Installed a ccv filter
3. Less idling time - unless using high idle mod
4. Started adding either stanadyne or Diesel Kleen every tank
5. Installed the blue spring and improved the fuel pressure by 10+ psig
6. Had weak batteries and later a failed FICM - had them replaced on warranty
7. A little more consciencious about minimixing short trips and try to regularly give it a WOT or two
Ford has stated somewhere where poor combustion (unburned fuel) can make the intake area under the EGR valve look "wet-ish", and can be mistaken for a leaking oil cooler. I just tried to shotgun everything that I could do to improve combustion. Seemed to work.