I’ve actually answered this one once before. :D
This is my theory. I figure the death smell only comes when they sleep as they are basically dead. Possibly a defense mechanism to hopefully keep humans and hunters away, otherwise being in public would be a problem. It didn’t deter the Frog brothers, but it slowed them down a little.
I’ve always imagined as a group they all smell like they’ve spent a thousand summer nights sleeping in trees with a combination of grease and engine oil from their bikes.
Individually, David would smell of cigarette smoke and leather, all very natural; earthy.
Dwayne would smell the same, without the leather; metallic, like he’s been working on his bike for nights on end, with a hint of something such as sandalwood, and whiskey on his breath.
Marko, he would smell of frankincense and myrrh. A touch of old spice and a little copper.
Paul would smell heavily of weed at all times with a hint of bubblegum or cotton candy, something sweet to mask the skunk odor and draw in the girls.