Does drooping always mean underwatering?
No. Overwatering and root problems can also be associated with wilting. Soil moisture and drainage are the first checks, not the final diagnosis.
Can I test drooping by watering again?
Avoid using more water as a test when the mix is already moist or wet. First check deeper in the pot and make sure water can drain.
When should I inspect roots?
Inspect accessible roots when drooping persists with wet soil or is accompanied by discoloration, softness, or an unusual smell. Those signs do not confirm one cause by themselves.