Hi Mike,
If one plug is not firing at all, you'll know that by the idle (assuming your idle speed is set correctly) and you'll know by driving it. You'll lack power and you'll feel a roughness while driving. Idling will be a jittery affair and at times your engine might seem like it is going to die (especially if your idle speed is around 525~550 rpm).
As for the multi-tester, if you're getting 0 ohms when you test each wire from end to end, that's what you want. Some meters will make a noise when the wire successfully conducts electricity. When you say you got nothing, I'm confused. Do you mean you got an open wire?
