A few weeks or so ago every time I walked out my back door I would think, 'What is that awful smell?' Finally it hit me that it must be a dead critter. Sure enough it was a dead possum. Looked like it crawled under the back steps to escape a predator. Ick. (But that's nature.) So first I called our city govt. and they had someone remove it about an hour later. Of course that doesn't get rid of the smell. Later that day I was talking to someone who had a similar situation. She gave me a less than helpful idea of what she used (said it was 'white charcoal'), but she told me that she bought it at one of our local hardware stores. They knew what she meant. It's called The Gonzo Odor Eliminator For Homes. Not sure what it actually is, but I can tell you that it works fast! Supposedly it's made of 'volcanic material'. So anyway, I have no ties or financial interest with the company — just saying.
Used to try the beer thing for slugs. We drank German beer at the time, so that's what we used. Unfortunately our German dog would drink the beer right after we'd placed it so perfectly. Oh well. I have heard that it works.