Does my breath smell?

It appears that Helicobacter pylori may be the cause of halitosis (aka 'bad breath') as well.

H. pylori is a very interesting bug. It appears to have first been identified in the 1800's, though the work didn't really go anywhere. The issue was readdressed in the early 80's, with the work of scientists Barry Marshall and J.R. Warren, who linked the organism to stomach ulcers. This was met with a fair bit of skepticism, but Marshall showed them (did he ever!) by drinking a flask of the bug and promptly coming down with a stomach ulcer. In addition to being a really stupid thing to do, it eventually earned them the Nobel Prize in 2005. There are also links between H. pylori and stomach cancer, which makes the issue of halitosis rather small potato's in the grand scheme of things. It's estimated that roughly 50% of the worlds population carries the organism, though only a percentage of those carriers ever present with any sort of symptoms.