For example, what would be inappropriately off topic to post to LessWrong discussion about?
I couldn't find an answer in the FAQ. (Perhaps it'd be worth adding one.) The closest I could find was this:
What is Less Wrong?
Less Wrong is an online community for discussion of rationality. Topics of interest include decision theory, philosophy, self-improvement, cognitive science, psychology, artificial intelligence, game theory, metamathematics, logic, evolutionary psychology, economics, and the far future.
However "rationality" can be interpreted broadly enough that rational discussion of anything would count, and my experience reading LW is compatible with this interpretation being applied by posters. Indeed my experience seems to suggest that practically everything is on topic; political discussion of certain sorts is frowned upon, but not due to being off topic. People often post about things far removed from the topics of interest. And some of these topics are very broad: it seems that a lot of material about self-improvement is acceptable, for instance.
Probably because it's so very very common and almost always utter bollocks.
People who would never think they were capable of comment on, say, nuclear reactor design with an hours study never the less think they're qualified to talk about the health effects of xyz based on about as much.
And sadly they get taken seriously, unlike in many other fields. news shows will include nuts who believe that vaccines cause autism for "balance" opposite the doctor but in the following segment on rocketry they don't feel the need to include someone who believes that the sky is a dome of water opposite the physicist for the sake of "balance".
It's a form of bikeshedding.
http://en.wiktionary.org/wiki/bikeshedding
Because health/biology is easy to relate to life around them(not the same as actually easy) and actions people assume it's easy and try to boost their status by making up waffle about it that sounds vaguely reasonable to laymen so it leads to a lot of useless waffle.
Actually, Doctors practice reflects little about what the scientific literature says about vaccines, or most anything else. Medical decisions are routinely made worse than randomly. Here's a recent review article. They reviewed all the articles for 10 years in a high impact journal. The majority of the articles surveyed study a new practice, but of the 27% that test an existing practice, 40% reverse the practice and 38% reaffirm. My remark on this is: 50%-50% would be what you'd expect if the result of the test were random. So this indicates they are doi... (read more)