The General public cannot get the 'cream puff' mentality out of their heads, which means driven to Church on Sundays with LOW miles. We are all like that to a certain extent. It was drilled into our heads growing up with gas engines.
When we sold our '08 Dynasty in the fall of '14, it had just shy of 70,000 miles on the 425hp Cummins. We picked up the coach new in April of '07 so we owned it for 7.5 yrs.
The consignment shop said customers would question the high miles because that's what customers do. At 70,000 miles, a diesel engine is barely broke in as long as it has full service records to prove good maintenance.
If I were you, I wouldn't shy away from a coach with 65,000 miles as long as they can prove that it has been serviced regularly. You would probably want to have a mechanic go over the engine no matter which motorhome you buy. As said many times on this site, a rarely used unit is not necessarily a good unit.
Safe travels,
MM.