Bruce Daisley is Director, YouTube & Display at Google. Here he examines the overuse of re-targeting in display buying and the reliance on "cookie bombing" to deliver perceived performance.

In his book, The Big Short, about the Sub-Prime lending crisis, Michael Lewis painted a fascinating picture of how a market failure happened. He described the world where the gulf of understanding between the trading floor and the boardroom was so vast that bosses effectively became estranged from the practices taking place in their companies’ names. The trades were so brain-achingly complex it was easier for bosses to leave the scribblers on the floor to get on with them.

It’s incredible that the world of digital advertising seems to suffer from the same gulf of understanding between practioners and marketers. It reflects especially poorly on our industry. In comparison to the PhD in braininess that Sub-Prime required, remarketing is like breezing through a Driving Theory test.

You know the logic of all of this. In days gone by ad inventory had a degree of exclusivity. Publishers might sell the majority of their space themselves and the remnant went to a single ad network. By using different networks, a buyer could add incremental reach to a plan. But today ad networks source much of their inventory from ad exchanges, offering the same ad impressions on the same sites. If an advertiser asks more than one network to chase their remarketing cookies for them the end result is self-competition.

There is evidence that this overuse of remarketing costs brands money - advertisers who use multiple networks end up doubling their CPA versus those who consolidate. This is not to mention the horrible user experience of the best prospects (people who’ve visited a website) being bombarded with offensive quantities of ads.

In this new order of the world there are two clearly different roles for ad businesses to play - remarketing and prospecting. Remarketing brings your visitors back, prospecting does the considerably harder job of finding new customers and bringing them to you. You would have thought that networks would have been falling over each other to demonstrate the value they can add prospecting for brands. Instead there is an attempt to hold back the tide.

The people running agency trading desks are impressively striving to provide leadership, proudly declaring their agreement with remarketing consolidation. Unfortunately they often sit a long way from the buying floor. Buyers might have been told what ‘the best practice is’ but in reality the execution of it is poorly policed. Some buyers seem more preoccupied with where their next lunch is coming from, rather than whether they are doing a bad buy. “We know it’s not right, but it works,” one buyer told me last month. Admittedly, relentless pressure to deliver volumes of conversions for clients doesn’t encourage long-term decision making. As a result it is still routine for the majority of network buys to power their plans by providing remarketing lists to 2, 3 or more networks. It is not uncommon for us to see 8 to 10 providers chasing the same cookie list across the web. This is truly crazy.

At the Exchange Wire conference last month, a representative of one of the established networks was asked their philosophy on remarketing consolidation. “We don’t advise advertisers to consolidate their remarketing,” he offered. I found this surprising. Surely it would be better for them to show the value of their technology to find new leads rather than encouraging their clients to compete against themselves through exchanges (not to mention hounding their existing visitors with yet another ad).

This is why Google UK took the step of publishing our performance benchmarks last month. We don’t know if we’re the best - but most of our advertisers express delight with the results we achieve. We decided that the best way to challenge the industry is to be more transparent and show what results our technology can produce. For example, an ad using keyword contextual targeting is 8 times more effective that the industry average. We shared our average prices and performance rates for remarketing, contextual and other targeting types. This will enable advertisers to make informed decisions based on a clear view of results. We hope that this encourages other companies to open their doors and increases competition to deliver the best possible results.

For the good of the industry it’s time that the best practice for remarketing was nailed for once and for all. This week we’ve released a booklet explaining our take on this. Ideally it will help trading desks place something substantial in the hands of their agency buyers so we can move the debate on.