Re: used outboard 150
Difficult decision, generally it is safer to stay with a freshwater motor, but if the boat was docked well into freshwater that motor may have been well flushed in returning to port.
Ask the owner if he is the original owner and where has the boat been kept. Google the port to see if it is fresh or salt. If the boat was always trailered it can be difficult to determine if the owner has been religious about flushing after each run in the salt.
And lastly, why is he selling the motor? What has he replaced it with.
Is the owner willing to have an independent inspection? It the price of the motor good enough to consider calling a local shop to go inspect the motor to give you a better idea of its condition?