For example, Adwords defaults into advertising on every device which now includes TVs. This channel would never work for our business (an app that integrates with GitHub), and I'm sure this would work badly for many other businesses. We only found it by digging into the campaign stats once it had launched.
It also strikes me how long the approval takes for new ads - 48 hours. How many advertisers drop off in that time? That feels like a real value add thing to focus on.