Based upon the other reviews, I was very hopeful that this would be a good product. However, I have tried it in the fireplace (ash odor), basement (musty odor), son's dorm room (who knows what that odor is), trash bin (old garbage odor) and generally around the house. I cannot tell a difference.
Washed it thoroughly before use according to directions. Kept the water level filled and ... nothing. Odors persist where they were difficult before.
If you read the instructions, descriptions and reviews, you will notice a common thread:
you must wait many hours for it to work. I think that what is happpening when people report that it "works" is that these odors dissipate on their own in that time.
One reviewer even pointed out that if you place the SmellKiller, wait and open the windows, in a short time the odor is gone.* I suspect that opening the windows is what did it, not the SmellKiller.
If it seems too good to be true ...you know the rest.