I'VE BEEN FACING THE SAME DILEMMA. THREE YEARS AGO I BOUGHT A HOUSE, RIPPED UP THE CARPET IN THE LIVING ROOM & FOUND THE SAME BLACK STAINS UNDER THE CARPET. I TRIED EVERYTHING UNDER THE SUN TO CLEAN THE FLOOR. I EVEN RENTED A FLOOR SANDER & STRIPPED THE FLOOR TO NO AVAIL. AFTER THREE YEARS THE SMELL IS STILL THERE & MOISTURE HAS REMAINED IN THE FLOOR. AFTER THREE YEARS I WOULD SAY IT'S NEVER GOING TO DRY! I WAS UNABLE TO COMPLETE THE PROJECT & HAVE LIVED WITHOUT A LIVING ROOM THE WHOLE THREE YEARS I'VE BEEN IN THE HOUSE LOOKING FOR A COST EFFECTIVE SOLUTION. I WANTED TO KEEP THE NATURAL WOOD FLOORS TOO BUT I DONT THINK IT IS POSSIBLE. I BELIEVE THE ONLY WAY TO GET RID OF THE SMELL IS TO COMPLETELY REMOVE THE FLOOR. BEFORE I DO REMOVE THE FLOOR I'VE DECIDED TO GO AHEAD & TRY TO PAINT THE FLOOR WITH A FLOOR PAINT & SEE WHAT THAT DOES BEFORE REMOVING THE FLOOR TOTALLY. THE PROBLEM IS IF YOU WANT TO REPLACE THE CARPET THE ODOR MUST BE SEALED FIRST. I'VE HEARD THAT BULLS EYE SHELLAC WOULD SEAL THE SMELL BUT I HAVENT FOUND THAT PRODUCT AT MY LOCAL RETAILERS. EVEN IF YOU HAVE THE SHELLAC IT'S HARD TO STAIN THE FLOOR TO BE ONE EVEN COLOR TO MATCH THE DARK SPOTS!!