The exposé even caught the non-profit USA for UNHCR inadvertently running ads on InfoWars, and it's going one step further by pulling all ads from YouTube. It and other organizations are asking if they can recoup the advertising money they spent on InfoWars' channels.

We've asked Google if it can comment on the findings. In a statement to CNN, a YouTube spokesperson declined to address how InfoWars slipped through the cracks of the sensitive subject filter and instead portrayed itself as striking a balance. It vows to "uphold free expression" even when it disagrees with ideas, but added that it doesn't allow ads on videos covering "sensitive and tragic events." InfoWars frequently promotes widely discredited conspiracies around such events, including the Parkland and Sandy Hook mass shootings.

The discovery and subsequent response highlight the ongoing challenges YouTube and some other ad-dependent services face. It's impractical for them to require manual approval for ads, but that automation also leads to offensive material slipping through the cracks -- not to mention debates over what "offensive" really means. YouTube's recently instituted policy on objectionable content helps, but it's clear the system still has some inconsistencies.

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