I've got this same problem on the J/30 I just bought. The surveyor noted it but found that the pump-out hose had separated from the deck fitting and concluded that this was the source of the smell.
The first thing I did was reattach it (it was a vacuum cleaner looking hose that was glued into a fitting which was then attached to the deck fitting, and the glue had come unattached).
After leaving the boat alone for a few weeks the smell seems almost worse. I don't see any leakage anywhere and cant find a single source of the smell.
Someone above mentioned that old hoses can stink. Does this mean the hoses themselves give off the odor, or that they start leaking raw waste (cause I cant find any leaked waste).
I'm trying to determine whether I should start replacing hoses or if my problem could be elsewhere.
Thanks - Dan
