To me, I don't see anything really out of whack, other than the brown coloration on the insulator. No fluffy black stuff to suggest a too-rich mixture and no oily places on the bottom of the plug threads or insulator. Gaps look decent, as does the general condition of the electrodes.
Are they the correct heat range, or something close? Being on the "cold" side might be the reason for the brown coloration from things not getting hot enough, long enough, to burn the deposits/coating off?
As long as they are firing reliably, just drive the cars and enjoy them. Before putting them back in, clean the electrodes' firing surfaces and gap just a tad wider then .035", like .038".
Years ago, a drag racing article on reading plugs stated that the only way to "read" a plug was to make a full run down the strip, then cut off the engine and coast to a stop on the return road. THEN pull each plug out and look at them. Otherwise, the author claimed, you would not get a true plug reading. FWIW
Just some thoughts,
CBODY67