No clue - the smell of oil on my tires from the blacktop roads I ride covers up any other smell on my bike. Except when I freshly lube the chain...mmm...

I suppose I could remove the saddle, but seeing as how the saddle hasn't been moved in oh, 5 years, and I know for a fact it's quite stuck, I don't think it's worth the effort. At some point, I'll have to do something about that.