I almost agree with you about the speculative nature of CPM based ads, but there's value in running branding campaigns, particularly for the kinds of companies

I almost agree with you about the speculative nature of CPM based ads, but there's value in running branding campaigns, particularly for the kinds of companies that advertise on our site (I work for Ars). It's awfully hard to measure that value in any kind of meaningful way, but brand awareness is worth spending money on in many cases.