Well, some rot traits are:
blackening, soggy leaves
soggy soil
non-crisp, soggy roots
So, basically, the key word is "soggy" LOL! Here's the clearest description of root rot...
Okay, ALOT of water goes into the soil. It bombards the air spaces in the soil, forcing the oxygen out. Without oxygen for the roots, the plants actually drowns and dies.
If you think your plant has root-rot, just let it drain a little, but DON'T let it get dry. Just let it dry until it is just moist. Then water it a little less, say, only keep a fourth of an inch in the water tray.
Hope this helps!
FTG