What's that smell?

I arrived home from work tonight to a stench in the air.  Greg had the day off so I was trying to guess what he'd been up to.  My first guess was he cooked something odd for lunch.  He did cook fish for lunch, but that wasn't the smell.  He led me upstairs and the scent became stronger.  He took the initiative to disconnect the radiators in the bedrooms, sand the area underneath and around the radiators and appy two coats of stain.  What a guy!  Once again, I'm a lucky gal.  A great start to the week ahead.