Earlier this week, The Wall Street Journal reported that for the past nine months, Gannett’s USAToday.com apparently delivered ad campaigns on websites other than those its advertisers had been expecting, and didn’t provide transparency into that fact in its reporting. This was only discovered after a researcher did some digging into ad campaign log files.

Unfortunately, this happens all too often, particularly when digital publishers use impression pools to fill out the campaigns that they have sold and are delivering.

Impression pools are baskets of third-party inventory — think long-tail ad networks — added to campaigns to help fill out the delivery volume and bring down the overall campaign CPM, because they tend to be composed of very cheap inventory.

In impression pools, dodgy inventory is a feature, not a bug. Do I know that’s what happened with USAToday.com? No, I don’t. However, it provides great context to resurface this issue.

Do advertisers understand exactly when and how digital campaigns they buy are enhanced with third-party inventory? Most probably don’t — and, as with so many similar issues in our industry, way too many advertisers don’t want to know.

I’m particularly worried about this issue because impression pools are already becoming a standard part of the connected TV ad world.

It’s logical that this has happened. CTV is a premium-priced ad channel that is very hot, and in which there’s both considerable advertiser demand and lots of premium inventory scarcity.

Rather than patiently wait to grow inventory the old-fashioned way by investing in content, marketing and promotion, some take the shortcut of buying cheap impressions off exchanges and repackaging them in their campaigns.

Given the understaffing at many agencies and advertisers today, the maniacal focus on lowering CPMs, and the heavily fragmented distribution and delivery channels into CTV inventory, the sector is not only ripe for abuse: It’s also hard to have real transparency into where all a campaign’s CTV impressions are coming from.

Just say no to impression pools. Please.

In impression pools — baskets of third-party inventory added to fill out delivery volume and bring down CPMs — dodgy inventory is a feature, not a bug.