At the Collision conference in New Orleans last month, I heard a marketing executive defend the practice of tracking consumers across their mobile devices. But then he offered some unexpected consumer advocacy.

Adam Berke, president of the advertising firm AdRoll, had spent the previous 15 minutes endorsing cross-device tracking as a logical response to the way we often start researching a purchase on a phone before completing it on a laptop or desktop.

Then he had some different advice for advertisers: Balance privacy with personalization, and protect the user’s “right not to be surprised.”

That “right” is hard to define

What would such a right amount to in practice? We already have a web in which ad networks can use cookies — tiny tags in ads that your browser downloads — to track our visits across sites. And those advertisers can then correlate that data with other identifiers, such as a phone’s electronic ID and your record of clicking on ads, to form a rich picture of your interests.

I followed up with Berke, who talked to me on the phone out of his San Francisco office to expound on the idea.

“You obviously want to do the right thing for both moral reasons and for business reasons,” Berke began.

In other words: Agencies don’t want to produce ads that are so shocking or creepy that they drive consumers to buy competing products.

“It’s something that we’ve talked about internally for a while,” he added.

But have those discussions provided an exact definition of the “right not to be surprised?” Not so much. Berke suggested part of that right involved retaining empathy for “the average person — not yourself as a marketing technology person, but what the average person would understand about online advertising.”

A privacy expert with a background in advertising couldn’t pin down the concept, either.

“‘Don’t Surprise People’ with what you are doing with their data has long been an informal guidance in the world of privacy, along with 'Don’t be Creepy,'” said Jules Polonetsky, CEO of the Future of Privacy Forum. “Back in my AOL and DoubleClick days, we would often turn down a proposed ad campaign, telling the business people that consumers would be surprised, or worse, creeped out!”

But, he continued in an e-mail, the squicks-us-out line shifts.

“There was a time when ad networks didn’t retarget users in a way that made people feel they were being followed,” he said.

Retargeting is the fine art of showing you ads at third-party sites for a product you’d checked out at a different site — see also, why looking at one refrigerator at Amazon ensures that every other ad you see elsewhere includes a pitch for somebody’s fridge. It’s a core part of AdRoll’s services.

Berke obviously doesn’t think that’s wrong. When I pressed him for what would go too far, he suggested that figuring out somebody’s email address from their browsing pattern and then e-mailing them an offer would cross his own line.

Well, a Paris company called Criteo (CRTO) does something much like that, cross-referencing e-mail databases provided by clients to allow a shopping site to e-mail a visitor otherwise unknown to the retailer.

That and other products have proven sufficiently popular with advertisers that the stock market now values the firm at $2.72 billion.

We don’t want to be bored, either

I have yet to get that sort of upsetting experience myself. My recurring complaint with ads involves not surprise but boredom: Why do I keep seeing ones I’ve seen before, and which didn’t interest me the first time?

Without fail, I will finish reading a story — which should make me one of a site’s best readers — and get treated to the same grid of ads for stories “around the web.” Most of them point to vapid celebrity content that a proper marketing database would reveal I have no interest in.

And yet I have written and continue to write for many sites that run those “remnant” ads, automatically inserted by algorithms to fill spaces that the publisher’s own ad salespeople couldn’t fill.

Before you all say “ad blockers,” I don’t think they’re an answer either. They punish non-obnoxious ads, too. If they take off they’ll only speed a migration to news apps that will only increase the leverage of Apple (AAPL) and Google (GOOG) over publishers.

(I will use Safari’s Reader Mode to punish obnoxious sites by displaying only the text and images of a story.)

We may not like advertising, but it has to work at some level if we’re going to continue to get stuff to read for free.

I got a fresh reminder of that earlier this month when I learned of the impending closure of the The Toast — an artsy, essay-driven site that I saw founder Mallory Ortberg describe as “modest, achievable success” before an approving audience at the XOXO conference last September.

That hit home for me, since I write for ad-supported sites and also approvingly cited Ortberg’s testimony in my report from that indie-creativity gathering. There has to be some way in which we wind up with fewer but more valuable ads that can still support not just mainstream sites but quirkier fare. For that to happen, ads just need to neither bore me nor shock me ... and I really don’t know how we’ll get there.

Email Rob at [email protected]; follow him on Twitter at @robpegoraro.

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