AFR misleading? Plugs tell a better story?

Sure if you’re in the middle of the desert trying to get home or tying to make the next round without parts, but if you’re in your driveway diagnosing problems trying to eliminate variables I can’t see why you would.
Because the new crap part you replace it with can loosen as well. I've had Standard, Blue Streak brass rotors loosen in the past and the screw/epoxy works.