I found some suspicious distortion on a C0G cap.
After investigation, the culprit was not the cap, but solder flux residue. Isopropyl alcohol and toothbrush removed the distortion.
After investigation, the culprit was not the cap, but solder flux residue. Isopropyl alcohol and toothbrush removed the distortion.
Solder flux residue is probably fairly similar in properties to carbon composition resistor filling!