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https://digiday.com/media/fewer-advertisers-means-more-bad-ads-from-ad-exchanges/
Fewer advertisers means more bad ads from ad exchanges

Larger advertisers fleeing from the open marketplace has cleared the way for smaller, sometimes subpar advertisers, slipping through filters and appearing on publisher sites.
Magazine publisher Immediate Media has seen a handful of low-quality ads — retailers selling products from overseas containing adult-rated content — crop up in its BBC Good Food app or on pre-roll video ads. One bad ad only had 10 impressions, said digital advertising strategy director Dominic Perkins.
“Through this whole lockdown period I’ve gone to our [supply-side platform] partners to ask what protection they have in place for bad debt — that was our biggest risk — and how they manage dodgy ads coming through,” he said.
The special-interest publisher doesn’t have a specific ad-verification partner to catch these ads, instead, it works with U. K.