Spark plug reading?

The plugs are champion rc12yc and they have about 6 months of use on them. I swapped them out for a new set I already had on hand.

They may have some oil on them, they're the same plugs that I used for break-in and I put less than 2000 miles on the car this year. I have a msd 6al that will be going in while the car is in hibernation for the winter.

I didn't see any gray or silver flecks on them when I was eyeballing them...it might be from the flash on the camera, but I'll recheck.

After I swapped them out, I started the car up to get the new antifreeze I put in cycled through the engine. After idling long enough to get it warmed up, I decided to pull some of the plugs and found that the front four (1,2,3,4) are completely black and the rear four (5,6,7,8 ) still look new. It looks like the idle circuit on the secondaries isn't working and I'm going to pull the holley for a rebuild before next season.