If a motorcycle is listed with water/flood damage, will it still run as-is or does it need work first?

Assume it will need work. Flood exposure on a motorcycle commonly affects the electrical system, carburetor or fuel injection components, and internal engine parts if water reached the cylinders — even if it appears to run at intake, corrosion and electrical issues often surface later. Budget for a full mechanical and electrical check before relying on it, rather than assuming the run-status field tells the whole story.