Last year when new boat shopping odors were high on the list of boats to question. On a newer Selene a leak in the holding taking fittings were found. On a Nordhavn 62 a bad exhaust vent on a diesel heater appeared. Whether new or old some odors can be traced to original build defects, especially water leaks that never show up until a panel is pulled off.
Best to track down the reason for the smell if you choose to some day sell your vessel.