We purchased our coach about 18 months ago from a person who owned a dairy farm. He kept it quite close to the cows, it did have a aroma when we brought it home.
We thought the cows were the only culprit but some drain connection issues in the slide issues also contributed to the odoriferous enhancement. There was still a slight smell even after we had the tanks cleaned.
Last week we purchased a ozone generator and placed it in the coach.
Ozone is not to be inhaled but does convert back to oxygen in a very short time
After running the ozone generator for 2 hours and then allowing another hour for the ozone to dissipate we were extremely satisfied with the results.
All the stink was gone!!
It actually smelled like a brand new coach, You could truthfully smell the plywood in the cabinets
The best part is it only cost about $50 delivered from Amazon, The piece of equipment is not much bigger then a regular toaster, about the size of a 4 slice
Totally amazed