I have taken a chain saw/mower/motorcycle plug wrench and built a special tool to remove those hard to get to plugs.
The joys of changing them on big block ‘67-68 Mustangs and ‘66-67 Fairlanes cannot be described. At least in polite company.
I had changed the plugs a couple of times before and they always looked good. Probably the unleaded gasoline was more responsible than anything else.
There were a couple on the driver side which were really rough. I probably could not have gotten them out without a universal joint between the ratchet and plug socket.
Getting the plug wires off was also a fun job.