2300 hours with proper care and attention is peanuts on a diesel. A good mechanic can tell fairly accurately by looking and listening. Oil analysis is a good indicator too as long as its not fresh oil. Maintenance records are good. Pull the injectors and they will tell a tale to the experienced eye.
General cleanliness is a nice indicator too.
High hours alone is no reason to reject. Low hours are no reason to accept. Do the assessment or pay to have it done. I was looking for a really good price on a boat, so I purchased one that cosmetically was not great and needed a lot of minor repairs. I am happy with that decision.