As Kirk in Coronation once said "Oh aye, you can't beat the smell of a wet dog's head, best smell in the world, that!".
However, I've never owned a dog of some sorts or other but do have a cat with bad breath (he has that from when I got him as a kitten, he's now ten years old. I did get him checked out for tooth-related issues but nothing showed up, so had to accept that he just has bad breath).
However, much higher up in the list is cat's fart. Man alive, if Saddam Hussein is still alive and is able to bottle what comes out of Chad's backside, he'd win the Middle East war hands down with it.