I have been pasting to BitBin.it for a long while now, and lately I have noticed an interesting trend.
Pastes that have virtually no content, or only a link, or a few words tend to only get between 150 and 450 hits, however, pastes that contain more useful information tend to get more hits.
So my theory is, the more relevant information is inside a single paste, the more hits that paste will get, and the more ads are display, paying out more Satoshi in turn.