How low does it continue to go?
As coils age, they have a tendency to change resistance--it can go up or down, depending on what's happening with that thin, fragile wire.
If your atty reads a very high resistance (K Ohms, M Ohms.. or infinite Ohms) then it is "open," which means that the coil is broken, which means it's dead.
If it isn't quite "open", or broken, yet, but reads substantially higher resistance than the stock numbers.... it is fixin' to go open--just as bad.
If you are getting very low resistance, less than .5Ω, a short is about to happen or has happened.
0Ω reading indicates a short.
With dual coils, if one coil pops, the resistance of your atty will double. So, with 1.5Ω dual coil atty, 3Ω (or thereabouts) reading indicates that one coil is dead and the other one is still alive and well.