- Answers with formatting (usually markdown; I don't see much HTML) tend to do a lot better than unformatted answers.
- And, even when a question uses formatting, the amount of formatting influences the relative popularity (as measured by vote count; accepted answer is a worse measure because once someone accepts an answer they're less likely to return to the question when new answers- with better markdown- are submitted, whereas a steady stream of newcomers keeps vote counts relatively current).
Of course, that's just anecdotal observation.
Are there are any numbers on that? A very rough measure being number of tags v. number of votes on average.
And if there aren't numbers, I guess my question is... Does anyone else see this trend?