I don't see ads in newspapers, or on web pages. It's a very useful filter to have.
At the "JOurnalism matters" summit on Saturday one Sunday paper admitted to being "quite driven" by the concerns Keith talks about; they watch their affiliated website closely during the week, and what gets the page-views plays a big role in story selection. But it seems to be driven more by the strong competition for readership between the major Sunday papers than by a desire to maximise ad revenue.
Can't say who, as the discussion was under Chatham House rules.