TOPIC:

In troubleshooting intermittent cylinder drop out on my KZ305, I found both NGK D8EA plugs read 60 - 80K ohms. I bought a new set of plugs. One plug is 2.5 ohms, the other is 20K ohms.
Decided to check a bunch of other plugs laying around in the garage ,both used and unused. Readings were all over the place 1 ohm to readings in the meg ohms. I'm using a good Fluke meter with sharp pin probes.
I often check resistance of caps, wires, and coils, but never plugs before this. 

I just checked 4 new plugs and 4 old plugs (all D8EA).

Of the new ones, two measured around 0 ohms, and two measured around 20 to 50 ohms.  I scratched and played around with them and the two non-zero plugs never got near 0 ohms.

Of the old ones, which came out of a perfectly running bike, one was fully open.  two were in the 50 to 100 ohm range and very inconsistent.  And one was near 0 ohms.

So I guess the range is anywhere from 0 to infinity, if that narrows it down. 

I've busted apart a few plugs back in the day to make fittings for dial indicators and air-connections, but never really paid attention to the electrode. I always thought it was a single piece of metal, but then that probably is not the case since one end is threaded and the other end is super hard to hold up to sparks and combustion.  Maybe the NGK website has some info on that.

I had similar testing results. I had used 4- B8ES that were in a running engine. I cleaned them up using a propane torch, came out surprisingly nice. I had only one with O resistance. The other 3 were all over the map. I can check again if actually values would be needed.