- I flagged one story in my time on HN (< 2 yrs). It was obvious spam (referrer included and went to a webstore; unrelated title).

- I see newer stories thanks to some chrome extensions showing a 2 column layout. I rarely upvote though as I feel I am too inexperienced to decide what others should find interesting.

- I upvote comments that made me learn something. I downvote "redditism", flaming etc.

Just as another data point.