Hell, couldn't any oil do that? Vegetable oil, 3-in1, WD-40, used motor oil....well, wouldn't smell like poop, for sure. Your city treatment plant may not like you, tho.
unbelievably, after viewing this post and thinking how ridiculous and slightly awkward, I visited my parents this weekend and as I laid down in a nice hot bath, there on top of the lavatory reservoir was a small £6.99 spray bottle of Poo Pourri. I used it. it smelt nice.